Silicon Nanostructure Active Materials for Lithium Ion Batteries and Processes, Compositions, Components and Devices Related Thereto

ABSTRACT

The present invention relates to nanostructured materials for use in rechargeable energy storage devices such as lithium batteries, particularly rechargeable secondary lithium batteries, or lithium-ion batteries (LIBs). The present invention includes materials, components, and devices, including nanostructured materials for use as battery active materials, and lithium ion battery (LIB) electrodes comprising such nanostructured materials, as well as manufacturing methods related thereto. Exemplary nanostructured materials include silicon-based nanostructures such as silicon nanowires and coated silicon nanowires, nanostructures disposed on substrates comprising active materials or current collectors such as silicon nanowires disposed on graphite particles or copper electrode plates, and LIB anode composites comprising high-capacity active material nanostructures formed on a porous copper and/or graphite powder substrate.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to nanostructured materials for use inrechargeable energy storage devices such as lithium batteries,particularly rechargeable secondary lithium batteries, or lithium-ionbatteries (LIBs). The present invention includes materials, components,and devices, including nanostructured materials for use as batteryactive materials, and lithium ion battery (LIB) electrodes comprisingsuch nanostructured materials, as well as manufacturing methods relatedthereto. Exemplary nanostructured materials include silicon-basednanostructures such as silicon nanowires and coated silicon nanowires,nanostructures disposed on substrates comprising active materials orcurrent collectors such as silicon nanowires disposed on graphiteparticles or copper electrode plates, and LIB anode compositescomprising high-capacity active material nanostructures formed on aporous copper and/or graphite powder substrate. The present inventionincludes active material nanostructures and methods of manufacturingrelated to nanostructure processing, including electrochemicaldeposition (ECD) of silicon nanostructures on LIB anode active materialsand current collectors. The present invention also relates to LIBmaterials including binders, electrolytes, electrolyte additives, andsolid electrolyte interfaces (SEIs) suitable for use in LIB anodescomprising silicon and graphite materials, as well as components,devices, and methods of manufacturing related thereto.

2. Background of the Invention

Conventional LIBs suffer from poor capacity, energy density, and cyclelife. Silicon (Si) has been studied extensively as an active material inLIBs due to its appealing characteristics, including its hightheoretical specific capacity of ˜4200 mAh/g for lithium (Li) and itslow discharge potential. Si has slightly higher voltage plateau thanthat of graphite, so it has attractive safety characteristics. Si isabundant and inexpensive material, and lithiated Si is more stable intypical lithium-ion battery electrolytes than lithiated graphite.

Despite the attractive characteristics of silicon, commercializationattempts to utilize Si as an active material have been unsuccessful.Several factors contribute to this lack of success, including the lackof suitable methods available for mass producing high-quality Si-basedanodic materials, the lack of solutions to address the detrimentalconsequences of the high volumetric expansion and contraction of Siduring lithiation and delithiation, and the lack of solutions to addressthe low intrinsic conductivity of Si. There exists a need forhigh-quality, cost-effective Si-based anodic materials for LIBs;materials, composites, and LIB components for use in Si-based LIBs;methods for producing and utilizing such materials, and related LIBdevices and components and methods related thereto.

Traditional lithium batteries, including lithium-ion batteries (LIBs),typically comprise an anode, a cathode, a separator material separatingthe cathode and anode, and an electrolyte. The anode of mostcommercially available LIBs generally includes a copper foil currentcollector coated with a mixture of graphite powder and a bindermaterial. The cathode of most commercially available LIBs generallyincludes an aluminum foil current collector coated with a lithiumtransition metal oxide based cathode material. Traditional LIB anodesinclude intercalation-based active materials, such as graphite, whichhave limited charge capacity and cannot meet the rising demands ofhigher energy density, higher power density, and longer batterylifespan. Extensive research and development efforts have been dedicatedto lithium (Li) alloying active materials for LIBs, such as silicon(Si), which has a theoretical charge capacity of ˜4200 mAh/g. However,several issues have prevented commercialization of silicon-based LIBs.

Thin film Si active materials have been the subject of recentinvestigation for use in LIBs, but thin film Si lacks the high surfacearea of nanostructures and is susceptible to pulverization upon highvolumetric flux. Low-temperature methods for producing Si nanomaterialshave included ball-milling Si to produce Si powder active materials, butsuch methods result in low-quality Si particles having large,inconsistent particle sizes and low crystallinity.

Production of high-grade silicon nanostructures for LIB active materialstypically involves chemical vapor deposition (CVD) or wet chemistrytechniques, including high-temperature catalyzed growth of siliconnanostructures such as silicon nanowires. For example, such methods aredisclosed in U.S. Pat. Nos. 7,842,432 and 7,776,760, U.S. patentapplication Ser. Nos. 12/824,485 and 12/783,243, and U.S. ProvisionalPatent Application Ser. No. 61/511,826, the disclosures of each of whichare herein incorporated by reference in their entireties. Typicalmethods of manufacturing silicon-based nanostructures include using gold(Au) as a catalyst material for catalyzed growth of siliconnanostructures at high temperatures. Gold is widely used as a catalystmaterial due to its high chemical stability, but since gold isexpensive, it is not an ideal material for use in mass production ofsilicon-based materials. Copper catalyst materials have been proposed asan alternative to gold for catalyzed growth of silicon nanostructuresfor LIB active materials, as disclosed in U.S. Provisional PatentApplication Ser. No. 61/511,826, the disclosure of which is incorporatedby reference herein in its entirety.

There exists a need for cost-effective methods of mass-producinghigh-quality silicon-based materials suitable for use in LIBs,particularly for use as active materials in LIB anodes. Further, thereexists a need for low-temperature processes which do not require the useof catalyst materials for production of such silicon nanostructures.Further, there exists a need for improved control over the physical andchemical characteristics of such silicon nanostructures duringproduction to ensure proper device performance. Further, there exists aneed for high quality silicon active materials having improved bondstrength with the substrate to which the silicon is attached.

Additionally, there exists a need for materials, components, devices,and methods which accommodate the high volumetric expansion andcontraction of silicon which occurs during lithiation and delithiation.Problems associated with the high volumetric changes of silicon includeactive material degradation, unpredictable changes to the activematerial structure, exfoliation of anodic materials from the currentcollector, loss of conductivity, SEI degradation, inadequate or excessSEI formation, and undesirable side reactions due to excess siliconactive sites. These side effects contribute to unpredictable changes inthe battery materials and system, thereby causing large hysteresis inthe battery system's operation characteristics.

The present invention provides solutions to these and other problems,including solutions which provide control over the battery material andcomponent characteristics both during production and throughout themultiple charge cycles and in the various conditions to which thebattery is exposed. There exists a need for LIB binder materials,electrolyte materials, and SEI materials or layers suitable for use inLIB anode materials comprising Si active materials, particularly Si andgraphite active materials.

BRIEF SUMMARY OF THE INVENTION

The present invention includes novel, cost-effective methods forproducing high-quality, silicon-based materials for use in LIBcomponents and devices, particularly silicon-based LIB anodes. Thepresent invention allows for highly controllable, low-temperatureprocesses for producing such silicon materials, particularly siliconnanostructures. Further, the present invention includes uncatalyzedproduction of such silicon materials, whereby catalyst materials andhigh temperature processes are not required. These processes of thepresent invention allow for the production of high-quality materialswhose physical and chemical characteristics can be highly controlled tomeet specific requirements consistently. These high-quality materialsprovide consistency and predictability of battery system performance andallow for control over changes to these materials and battery devicesthroughout the multiple charge cycles and various conditions to whichthey are subjected. The high-quality materials of the present inventionprevent irreversible, undesired side effects which contribute tounpredictable and detrimental changes in LIB devices and cause largehysteresis in battery operation characteristics.

The present invention includes methods for directly depositing discretenanostructures comprising at least one high-capacity LIB active materialonto a substrate via electrochemical deposition, as well ascompositions, devices, and components related thereto. In preferredembodiments, Si is electrochemically deposited directly onto one or moreactive material and/or the current collector structures to form aSi-based LIB anode. In one example embodiment, Si is electrochemicallydeposited onto a copper (Cu) current collector, such as a Cu plate,mesh, or sponge, which can be used as a LIB anode material. In anotherexample embodiment, Si is electrochemically deposited onto graphiteparticles to form a Si-graphite composite LIB anode material. Thisapproach allows for low temperature, catalyst-free, and growthtemplate-free production of active material nanostructures suitable foruse in LIB anodes. This approach allows for production ofhighly-crystalline Si nanostructures at low growth temperatures andimproved control over Si deposition and the physical and chemicalcharacteristics of Si. Further, this approach allows for improvedadhesion between Si nanostructure active materials and the currentcollector and/or active materials.

The present invention further includes binders, electrolytes andelectrolyte additives, and SEI materials and layers suitable forSi-based LIB anode active materials, including Si and graphite compositeanodic materials. These materials provide improved interaction withSi-based materials compared to traditional LIB materials which are notdesigned to interact with Si materials and cannot handle the volumetricexpansion of high-capacity active materials during lithiation.

Additional features and advantages of the invention will be set forth inthe description that follows, and in part will be apparent from thedescription, or may be learned by practice of the invention. Theadvantages of the invention will be realized and attained by thestructure and particularly pointed out in the written description andclaims hereof as well as the appended drawings.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory and areintended to provide further explanation of the invention as claimed. Itshould be appreciated that the particular implementations shown anddescribed herein are examples of the invention and are not intended tootherwise limit the scope of the present invention in any way. Indeed,for the sake of brevity, conventional electronics, manufacturing,devices, nanostructures, other functional aspects of the systems,components of the individual operating components of the systems, andmethods related thereto, may not be described in detail herein.

For the sake of brevity, each and every possible combination ofmaterials, crystal structures, crystallinity, morphology, shape, andsize for the active materials, substrates, substrate-active materialcomposites, binders, electrolyte materials, and SEI layers and materialsmay not be explicitly described herein. However, the present inventionincludes any combination of the individual features described hereinwith respect to the active material nanostructures, substrates,substrate-active material composites, binders, electrolyte materials,SEI layers and materials and additional compositions, structures, anddevice components. Further, although each possible variation of therelated processes of the present invention may not be described inexplicit detail herein, the methods of the present invention includecombinations of the individual process parameters, and the modificationsand variations thereof, described herein. As will be understood bypersons of ordinary skill in the art, the individual features of eachembodiment of the present invention can be modified to achieve thedesired result. Such modifications are included in the scope of thepresent invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated herein and form a partof the specification, illustrate the present invention and, togetherwith the description, further serve to explain the principles of theinvention and to enable a person skilled in the pertinent art to makeand use the invention.

FIGS. 1A and 1B show electrolytic cells for conventional electrochemicaldeposition (ECD) techniques.

FIGS. 2A-2K show nanostructures comprising at least one LIB activematerial deposited on a substrate using one or more ECD techniques ofthe present invention.

FIGS. 3A-3I show nanostructures having different or varying materialcompositions throughout different spatial regions of the individualnanostructures.

FIGS. 4A-4D show scanning electron microscope (SEM) images of a graphitefoil substrate.

FIGS. 5A-5C show photographs of various composite LIB anode structurescomprising a graphite foil current collector substrate and discrete Sinanostructures formed directly on the graphite foil according to one ormore ECD methods of the present invention.

FIGS. 6A-22B show SEM images of discrete Si active materialnanostructures formed on a graphite foil substrate according to variousECD methods of the present invention.

FIG. 23 shows a graphite foil substrate having a graphite powdersubstrate formed thereon.

FIGS. 24A-24C show SEM images of the graphite powder layer of FIG. 23prior to Si deposition using one or more ECD processes of the presentinvention.

FIGS. 25A-25D show SEM images of a graphite powder layer having Sinanostructures formed thereon using one or more ECD processes of thepresent invention.

FIGS. 26A-27B show photographs of a porous copper (Cu) substrate havinga graphite powder substrate material disposed therein.

FIG. 28 shows an optical image of a porous Cu mesh substrate materialprior to deposition of Si nanostructures thereon.

FIG. 29 shows an optical image of a porous Cu mesh substrate having Sinanostructures formed thereon according to one or more ECD processes ofthe present invention.

FIGS. 30A-31D show SEM images of Si nanostructures deposited on graphitepowder which was disposed in a porous Cu mesh substrate scaffoldaccording to one or more ECD processes of the present invention.

FIGS. 32A-32D show SEM images of Si nanostructures formed directly on aporous Cu mesh substrate according to one or more ECD processes of thepresent invention.

FIG. 33 shows a Cu substrate material electrochemically deposited on agraphite foil substrate structure, and FIGS. 34 and 35 show theCu-graphite substrate of FIG. 33 after deposition of Si nanostructuresthereon using one or more ECD processes of the present invention.

FIGS. 36A-36C show SEM images of the Si nanostructures formed on theCu-graphite substrate shown in FIG. 34.

FIGS. 37A-37C show SEM images of the Si nanostructures formed on theCu-graphite substrate shown in FIG. 35.

FIGS. 38A-38C show LIB anode composite structures comprising particleand/or layer substrate structures.

FIGS. 39A-39F show ECD substrate structures having one or more regionscomprising surface features.

FIGS. 40A-40G, 41A-41I, and 42A-42C show substrate structures comprisingvarious surface features with discrete active material nanostructuresformed thereon.

FIGS. 43A-43F show various multi-layer substrates comprising surfacefeatures and discrete active material nanostructures formed thereon.

FIG. 44 shows an electrolytic cell for one or more ECD processes of thepresent invention.

FIG. 45A-45B show current-voltage profiles for various Si precursormaterials used in various ECD processes of the present invention.

FIG. 46 shows the current profile during Si deposition according to oneor more ECD embodiments of the present invention.

FIG. 47 shows an electrolytic cell including a magnetic stir plate forfluid motion in the electrolytic cell, according to one or moreembodiments of the present invention.

FIG. 48 shows an electrolytic cell for ECD of discrete active materialnanostructures on a particulate substrate.

FIG. 49 shows a porous working electrode having ECD substrate particlescontained therein.

Although the nanostructures of the present invention are shown ordescribed as individual nanostructures in certain figures ordescriptions herein, the present invention also includes pluralities ofsuch nanostructures having features similar to the individualnanostructures depicted herein. As will be understood by persons ofordinary skill in the art, the schematic drawings and elementsrepresented in the figures may not be proportionate in scale to theactual elements of the present invention.

The present invention will now be described with reference to theaccompanying drawings. In the drawings, like reference numbers indicateidentical or functionally similar elements.

DEFINITIONS

Unless defined otherwise, all technical and scientific terms used hereinhave the same meaning as commonly understood by one of ordinary skill inthe art to which the invention pertains. The following definitionssupplement those in the art and are directed to the current applicationand are not to be imputed to any related or unrelated case, e.g., to anycommonly owned patent or application. Although any methods and materialssimilar or equivalent to those described herein can be used in thepractice for testing of the present invention, the preferred materialsand methods are described herein. Accordingly, the terminology usedherein is for the purpose of describing particular embodiments only, andis not intended to be limiting.

As used in this specification and the appended claims, the singularforms “a,” “an” and “the” include plural referents unless the contextclearly dictates otherwise. Thus, for example, reference to “ananostructure” includes a plurality of such nanostructures, and thelike.

The term “about” as used herein indicates the value of a given quantityvaries by +/−10% of the value, or optionally +/−5% of the value, or insome embodiments, by +/−1% of the value so described.

A “nanostructure” is a structure having at least one region orcharacteristic dimension with a dimension of less than about 500 nm,e.g., less than about 200 nm, less than about 100 nm, less than about 50nm, or even less than about 20 nm. Typically, the region orcharacteristic dimension will be along the smallest axis of thestructure. Examples of such structures include spherical nanostructures,nanowires, nanospikes, tapered nanowires, nanorods, nanotubes,nanowhiskers, nanoribbons, nanodots, nanoparticles, nanofibers, branchednanostructures, nanotetrapods, nanotripods, nanobipods, nanocrystals,nanodots, quantum dots, nanoparticles, and the like. Nanostructures canbe, e.g., substantially crystalline, substantially monocrystalline,polycrystalline, amorphous, or a combination thereof. In one aspect,each of the three dimensions of the nanostructure has a dimension ofless than about 500 nm, e.g., less than about 200 nm, less than about100 nm, less than about 50 nm, or even less than about 20 nm.

An “aspect ratio” is the length of a first axis of a nanostructuredivided by the average of the lengths of the second and third axes ofthe nanostructure, where the second and third axes are the two axeswhose lengths are most nearly equal each other. For example, the aspectratio for a perfect rod would be the length of its long axis divided bythe diameter of a cross-section perpendicular to (normal to) the longaxis.

As used herein, the “width” or “diameter” of a nanostructure refers tothe width or diameter of a cross-section normal to a first axis of thenanostructure, where the first axis has the greatest difference inlength with respect to the second and third axes (the second and thirdaxes are the two axes whose lengths most nearly equal each other). Thefirst axis is not necessarily the longest axis of the nanostructure;e.g., for a disk-shaped nanostructure, the cross-section would be asubstantially circular cross-section normal to the short longitudinalaxis of the disk. Where the cross-section is not circular, the width ordiameter is the average of the major and minor axes of thatcross-section. For an elongated or high aspect ratio nanostructure, suchas a nanowire, the diameter is measured across a cross-sectionperpendicular to the longest axis of the nanowire. For a sphericalnanostructure, the diameter is measured from one side to the otherthrough the center of the sphere.

Preferably, the nanostructures formed according to methods of thepresent invention comprise highly crystalline nanostructures, e.g.,highly monocrystalline nanostructures, e.g., highly monocrystalline Sinanowires or other nanostructures. In preferred embodiments, thenanostructures are substantially monocrystalline and substantially freeof polycrystalline and amorphous materials upon formation. Preferably,the nanostructures are free of polycrystalline and amorphous materialsupon formation. Highly crystalline nanostructures can be formed by ECDprocesses of the present invention, and active material nanostructureshaving a high degree of crystallinity upon formation are preferred forthe LIB active material nanostructures of the present invention.

The terms “crystalline” or “substantially crystalline,” when used withrespect to nanostructures, refer to the fact that the nanostructurestypically exhibit long-range ordering across one or more dimensions ofthe structure. It will be understood by one of skill in the art that theterm “long range ordering” will depend on the absolute size of thespecific nanostructures, as ordering for a single crystal cannot extendbeyond the boundaries of the crystal. In this case, “long-rangeordering” will mean substantial order across at least the majority ofthe dimension of the nanostructure. In some instances, a nanostructurecan bear an oxide coating or other coating, including a shell or coatingof the same material as the core of the nanostructure but having adifferent crystal structure than the core of the nanostructure, or thenanostructure can be comprised of a core and at least one shell. In suchinstances it will be appreciated that the oxide, shell(s), or othercoating need not exhibit such long-range ordering (e.g. it can beamorphous, polycrystalline, or otherwise). In such instances, the phrase“crystalline,” “substantially crystalline,” “substantiallymonocrystalline,” or “monocrystalline” refers to the central core of thenanostructure (excluding the coating layers or shells). Unless otherwisespecified or distinguished, the general terms “crystalline” or“substantially crystalline” as used herein are intended to alsoencompass structures comprising various defects, stacking faults, atomicsubstitutions, and the like, as long as the structure exhibitssubstantial long range ordering (e.g., order over at least about 80% ofthe length of at least one axis of the nanostructure or its core). Inaddition, it will be appreciated that the interface between a core andthe outside of a nanostructure or between a core and an adjacent shellor between a shell and a second adjacent shell may containnon-crystalline regions and may even be amorphous. This does not preventthe nanostructure from being crystalline or substantially crystalline asdefined herein.

The term “monocrystalline” when used with respect to a nanostructureindicates that the nanostructure is substantially crystalline andcomprises substantially a single crystal. When used with respect to ananostructure heterostructure comprising a core and one or more shells,“monocrystalline” indicates that the core is substantially crystallineand comprises substantially a single crystal.

A “nanocrystal” is a nanostructure that is substantiallymonocrystalline. A nanocrystal thus has at least one region orcharacteristic dimension with a dimension of less than about 500 nm,e.g., less than about 200 nm, less than about 100 nm, less than about 50nm, or even less than about 20 nm. The term “nanocrystal” is intended toencompass substantially monocrystalline nanostructures comprisingvarious defects, stacking faults, atomic substitutions, and the like, aswell as substantially monocrystalline nanostructures without suchdefects, faults, or substitutions. In the case of nanocrystalheterostructures comprising a core and one or more shells, the core ofthe nanocrystal is typically substantially monocrystalline, but theshell(s) need not be. In one aspect, each of the three dimensions of thenanocrystal has a dimension of less than about 500 nm, e.g., less thanabout 200 nm, less than about 100 nm, less than about 50 nm, or evenless than about 20 nm. Examples of nanocrystals include, but are notlimited to, substantially spherical nanocrystals, branched nanocrystals,and substantially monocrystalline nanowires, nanorods, nanospikes,tapered nanowires, nanotubes, nanowhiskers, nanoribbons, nanodots,nanoparticles, quantum dots, nanotetrapods, nanotripods, nanobipods, andbranched nanotetrapods (e.g., inorganic dendrimers).

The term “heterostructure” when used with reference to nanostructuresrefers to nanostructures characterized by at least two different and/ordistinguishable material types. Typically, one region of thenanostructure comprises a first material type, while a second region ofthe nanostructure comprises a second material type. In certainembodiments, the nanostructure comprises a core of a first material andat least one shell of a second (or third etc.) material, where thedifferent material types are distributed radially about the long axis ofa nanowire, a long axis of an arm of a branched nanowire, or the centerof a nanocrystal, for example. (A shell can but need not completelycover the adjacent materials to be considered a shell or for thenanostructure to be considered a heterostructure; for example, ananocrystal characterized by a core of one material covered with smallislands of a second material is a heterostructure.) In otherembodiments, the different material types are distributed at differentlocations within the nanostructure; e.g., along the major (long) axis ofa nanowire or along a long axis of arm of a branched nanowire. Differentregions within a heterostructure can comprise entirely differentmaterials, or the different regions can comprise a base material (e.g.,silicon) having different dopants or different concentrations of thesame dopant.

A “nanoparticle” is a nanostructure in which each dimension (e.g., eachof the nanostructure's three dimensions) is less than about 500 nm,e.g., less than about 200 nm, less than about 100 nm, less than about 50nm, or even less than about 20 nm. Nanoparticles can be of any shape,and include, for example, nanocrystals, substantially sphericalparticles (having an aspect ratio of about 0.8 to about 1.2), andirregularly shaped particles. Nanoparticles optionally have an aspectratio less than about 1.5. Nanoparticles can be amorphous, crystalline,monocrystalline, partially crystalline, polycrystalline, or otherwise.Nanoparticles can be substantially homogeneous in material properties,or in certain embodiments can be heterogeneous (e.g., heterostructures).Nanoparticles can be fabricated from essentially any convenient materialor materials, e.g., the nanoparticles can comprise “pure” materials,substantially pure materials, doped materials and the like.

A “nanowire” is a nanostructure that has one principle axis that islonger than the other two principle axes. Consequently, the nanowire hasan aspect ratio greater than one; nanowires of this invention typicallyhave an aspect ratio greater than about 1.5 or greater than about 2.Short nanowires, sometimes referred to as nanorods, typically have anaspect ratio between about 1.5 and about 10. Longer nanowires have anaspect ratio greater than about 10, greater than about 20, greater thanabout 50, or greater than about 100, or even greater than about 10,000.The diameter of a nanowire is typically less than about 500 nm,preferably less than about 200 nm, more preferably less than about 150nm, and most preferably less than about 100 nm, about 50 nm, or about 25nm, or even less than about 10 nm or about 5 nm. The nanowires of thisinvention can be substantially homogeneous in material properties, or incertain embodiments can be heterogeneous (e.g., nanowireheterostructures). The nanowires can be fabricated from essentially anyconvenient material or materials. The nanowires can comprise “pure”materials, substantially pure materials, doped materials and the like,and can include insulators, conductors, and semiconductors. Nanowiresare typically substantially crystalline and/or substantiallymonocrystalline, but can be, e.g., polycrystalline or amorphous. In someinstances, a nanowire can bear an oxide or other coating, or can becomprised of a core and at least one shell. In such instances it will beappreciated that the oxide, shell(s), or other coating need not exhibitsuch ordering (e.g. it can be amorphous, polycrystalline, or otherwise).Nanowires can have a variable diameter or can have a substantiallyuniform diameter, that is, a diameter that shows a variance less thanabout 20% (e.g., less than about 10%, less than about 5%, or less thanabout 1%) over the region of greatest variability and over a lineardimension of at least 5 nm (e.g., at least 10 nm, at least 20 nm, or atleast 50 nm). Typically the diameter is evaluated away from the ends ofthe nanowire (e.g., over the central 20%, 40%, 50%, or 80% of thenanowire). A nanowire can be straight or can be, e.g., curved or bent,over the entire length of its long axis or a portion thereof. In certainembodiments, a nanowire or a portion thereof can exhibit two- orthree-dimensional quantum confinement. Nanowires according to thisinvention can expressly exclude carbon nanotubes, and, in certainembodiments, exclude “whiskers” or “nanowhiskers”, particularly whiskershaving a diameter greater than 100 nm, or greater than about 200 nm.

A “substantially spherical nanoparticle” is a nanoparticle with anaspect ratio between about 0.8 and about 1.2. Similarly, a“substantially spherical nanocrystal” is a nanocrystal with an aspectratio between about 0.8 and about 1.2.

An “active material” or “LIB active material,” as discussed herein,refers to one or more battery active materials—particularly LIB activematerials capable of being lithiated with Li ions and suitable for useas active materials in a LIB anode active material. The active materialscan include any suitable LIB active materials known in the art,including those mentioned herein.

As referred to herein, “inactive material” or “inactive materials”refers to materials which are either incapable of lithium insertion orhave negligible lithium insertion capacity compared to the counterpartactive material(s) in the LIB component formed according to the methodsof the present invention. Whether a material is active or inactive willdepend on characteristics of the LIB system in which the material isincluded. Inactive materials may be useful for purposes other thanproviding lithium capacity, such as to provide increased conductivity,to improve adhesion between the active material and the substrate, or toachieve certain characteristics of the active material during or afterthe electrochemical deposition process, as discussed in further detailbelow. The inactive materials may include inactive materials known inthe art, including those mentioned herein.

As used herein, a “current collector,” “current collector material,”“current collector structure,” or “LIB current collector” refers to aconductive material or structure which collects electrons releasedduring charge or discharge (i.e., lithiation or delithiation) in a LIBand transmits such electrons to or from the external circuitry connectedto the LIB from an external device. The current collector can includeany current collectors known in the art, including those mentionedherein.

As used herein, a “binder” or “binder material” refers to nonreactive,adhesive LIB components used to adhere one or more components together.For example, a binder material can be added to a substrate comprisinggraphite powder in order to adhere the graphite powder together to coatthe powder onto a substrate and form the LIB device or an ECD substrate.

In preferred embodiments, the one or more active materials formed viadirect ECD comprise discrete nanostructures rather than a continuousactive material structure such as a continuous film comprising theactive material. By “discrete” structures, as such terminology is usedherein with respect to active material nanostructures, it is meant thatthe structures include multiple independent and discontinuous domains ofthe material which forms the nanostructures, although such structuresneed not be entirely contiguous—i.e., “discrete” structures mayphysically contact one another unless otherwise specified. Thenanostructures can include essentially any desired type ofnanostructures, including, but not limited to, nanowires. Thenanostructures can comprise nanowires, nanorods, nanospikes, taperednanowires, nanotubes, nanowhiskers, nanoribbons, nanoparticles,nanofibers, nanocrystals, branched nanostructures, nanodots, quantumdots, spherical nanostructures, or other nanostructures, or anycombination thereof. Preferably, the nanostructures compriseone-dimensional, elongated, or high aspect ratio nanostructures. Forexample, the nanostructures can include nanowires, nanorods, nanospikes,tapered nanowires, nanotubes, nanowhiskers, nanoribbons, branchednanostructures, or other one-dimensional, elongated, or high aspectratio nanostructures, or any combination thereof. In preferredembodiments, the nanostructures comprise Si, e.g., Si nanowires. Morepreferably, the nanostructures comprise monocrystalline Sinanostructures, e.g., monocrystalline Si nanowires.

In certain embodiments, the ECD substrate surface can include discretesurface features to provide a modified substrate surface. By “discrete”substrate surface features or substrate structures, as such terminologyis used herein with respect to the ECD substrate and the ECD substratesurface, it is meant that the structures include multiple distinctregions or domains exhibiting the surface modification or surfacefeatures, or multiple distinct regions or domains exhibiting the surfacemodification or surface features to a greater extent than one or moreadjacent locations on the substrate surface. However, such modifiedregions on the surface or surface features need not be entirelycontiguous—i.e., “discrete” surface features may physically contact oneanother unless otherwise specified, so long as the discrete surfacefeatures provide regions at the substrate surface having distinguishablecharacteristics.

A “compound” or “chemical compound” is a chemical substance consistingof two or more different chemical elements and having a unique anddefined chemical structure, including, e.g., molecular compounds heldtogether by covalent bonds, salts held together by ionic bonds,intermetallic compounds held together by metallic bonds, and complexesheld together by coordinate covalent bonds.

An “alloy” is a metallic solid solution (complete or partial) composedof two or more elements. A complete solid solution alloy has a singlesolid phase microstructure, while a partial solution alloy has two ormore phases that may or may not be homogeneous in distribution.

A “porous” substrate contains pores or voids. In certain embodiments, aporous substrate can be an array or population of particles, e.g., arandom close pack particle population or a dispersed particlepopulation. The particles can be of essentially any desired size and/orshape, e.g., spherical, elongated, oval/oblong, plate-like (e.g.,plates, flakes, or sheets), or the like. The individual particles canthemselves be nonporous or can be porous (e.g., include a capillarynetwork through their structure). When employed for nanostructuregrowth, the particles can be but typically are not cross-linked. Inother embodiments, a porous substrate can be a mesh, fabric, or sponge.

A “carbon-based substrate” refers to a substrate that comprises at leastabout 50% carbon by mass. Suitably, a carbon-based substrate comprisesat least about 60% carbon, 70% carbon, 80% carbon, 90% carbon, 95%carbon, or about 100% carbon by mass, including 100% carbon. Preferably,the carbon-based substrate is highly pure carbon, e.g., greater than 98%or 99% carbon by mass. Most preferably, the carbon-based substrate is100% carbon by mass. Exemplary carbon-based substrates that can be usedin the practice of the present invention include, but are not limitedto, graphite, graphene, natural graphite, artificial graphite,highly-ordered pyrolitic graphite (HOPG), activated carbon, petroleumcoke carbon, mesophase carbon, hard carbon, soft carbon, carbon black,desulfulized carbon black, porous carbon, fullerenes, fullerene soot,carbon film or foil, carbon sheets, carbon paper, carbon powder, porouscarbon powder, carbon fibers, carbon particles, carbon microbeads,mesocarbon microbeads (MCMB), carbon nanotubes, carbon nanoparticles;graphene fibers, particles, or powder; graphite fibers, particles, orpowder; graphene foil, graphite foil, or other carbon-based structures,as well as combinations thereof. As used throughout, “carbon black”refers to the material produced by the incomplete combustion ofpetroleum products. Carbon black is a form of amorphous carbon that hasan extremely high surface area to volume ratio. “Graphene” refers to asingle atomic layer of carbon formed as a sheet, and can be prepared asgraphene powders. See, e.g., U.S. Pat. Nos. 5,677,082, 6,303,266 and6,479,030, the disclosures of each of which are incorporated byreference herein in their entireties. Carbon-based substratesspecifically exclude metallic materials, such as steel, includingstainless steel. Carbon-based substrates can be in the form of sheets orseparate particles, as well as cross-linked structures.

A “catalyst,” “catalyst material,” “catalyst particle,” or“nanostructure catalyst” is a material that facilitates the formation orgrowth of a nanostructure. Such terms are used herein as they arecommonly used in the art relevant to nanostructure growth; thus, use ofthe word “catalyst” does not necessarily imply that the chemicalcomposition of the catalyst particle as initially supplied in ananostructure growth reaction is identical to that involved in theactive growth process of the nanostructure and/or recovered when growthis halted. For example, as explained in U.S. patent application Ser. No.12/824,485, the disclosure of which is incorporated by reference hereinin its entirety, when gold nanoparticles are used as catalyst particlesfor silicon nanowire growth, particles of elemental gold are disposed ona substrate and elemental gold is present at the tip of the nanowireafter synthesis, though during synthesis the gold exists as a eutecticphase with silicon. Contrasting examples are disclosed in U.S.Provisional Patent Application Ser. No. 61/511,826, the disclosure ofwhich is incorporated by reference herein in its entirety. For example,when copper nanoparticles are used for VLS or VSS nanowire growth,particles of elemental copper are disposed on a substrate, and coppersilicide may be present at the tip of the nanowire during and aftersynthesis. As another example, when copper oxide nanoparticles are usedas catalyst particles for silicon nanowire growth, copper oxideparticles are disposed on a substrate, but they may be reduced toelemental copper in a reducing atmosphere employed for nanowire growthand copper silicide may be present at the tip of the nanowire during andafter nanowire synthesis. Both types of situations—i.e., situations inwhich the catalyst material maintains the identical chemical compositionand situations in which the catalyst material changes in chemicalcomposition, are explicitly included by use of the terms “catalyst,”“catalyst material,” “catalyst particle,” or “nanostructure catalyst”herein. Catalyst particles are typically nanoparticles, particularlydiscrete nanoparticles. As such terms are used herein, “catalystmaterials,” “catalyst particles,” or “nanostructure catalysts” aredistinct from “precursors” or “precursor materials” employed duringnanostructure growth, in that precursors serve as a source for at leastone type of atom that is incorporated throughout the nanostructure (orthroughout a core, shell, or other region of a nanostructureheterostructure), whereas a catalyst merely provides a diffusion sitefor nanostructure precursor materials and does not typically comprise asource material for the nanostructure.

With the direct electrochemical deposition methods of the presentinvention, LIB active materials can be simultaneously formed anddeposited onto the substrate. By “direct deposition” or “directelectrochemical deposition” of active materials, or active materials“deposited directly” or “electrochemically deposited directly,” as thoseterms are used herein, it is meant that the LIB active materials aregrown or formed by reduction of precursor materials directly on thedesired substrate surface via an electrochemical deposition process. Asused herein with respect to material deposition or nanostructureformation, these terms indicate that the active material is reduceddirectly onto the relative substrate, such that the active material isformed in direct physical contact with the substrate.

Unless clearly indicated otherwise, ranges listed herein are inclusive.A variety of additional terms are defined or otherwise characterizedherein.

DETAILED DESCRIPTION OF THE INVENTION Electrochemical Deposition of LIBActive Materials and Structures

Electrochemical deposition is a well-known process in the art for metalplating. As illustrated by FIGS. 1A and 1B, conventional processes ofelectrochemical deposition generally involve use of an electric field totransport metal ions 102 in a bath (or solution) 104 onto a cathodesubstrate 106. A power supply 108 supplies a direct current 111 from thecathode 106 to the anode 107, whereby electrons 110 are transported fromthe cathode 106 toward the anode 107. In one conventional technique, asshown in FIG. 1A, a solution 104 is provided in a container 112. Thesolution 104 is an electrolyte solution 104 containing one or moredissolved metal salts 103 and other ions that permit the flow ofelectricity through the solution 104. Dissolution or solvation of themetal salt creates metal ions 102 which can be reduced at the surface ofthe cathode 106 to coat the cathode surface with a solid layer 105 ofthe metal on the cathode surface. The positively charged metal ions 102in the solution 104 are moved toward the cathode 106 by an electricfield created by the direction flow of electrical charge through thesolution (i.e., the direct current applied to the system). Ions of themetal to be plated must be periodically replenished in the bath 104 asthey are drawn out of the solution 104 via the coating process. Inanother conventional technique for electrochemical deposition, as shownin FIG. 1B, the process includes use of a consumable anode 107, wherebythe anode 107 comprises the metal to be coated onto the cathode 106.This process is similar to that shown in FIG. 1A, except that the metalions 102 are provided by the metal anode source material. The directcurrent applied to the system forces electrons 110 to escape from theanode 107, leaving the anode with a net positive charge. In order toestablish equilibrium, positive metal ions 102 are forced from the anodesurface into the solution 104. The metal ions 102 are moved by theelectric field through the solution 104 toward the cathode 106, and themetal ions deposit onto the cathode surface to form a solid metal layer105. This process depletes the consumable anode 107, as illustrated inFIG. 1B.

For the sake of brevity, conventional electrochemical deposition (ECD)techniques, processes, materials, systems, and system components may notbe described in detail herein. However, the fundamentals of conventionalECD known in the art are included in the present invention, as will beunderstood by persons of ordinary skill in the art. Conventionalconcepts of ECD can be found in the Literature, e.g., Allen J. Bard &Larry R. Faulkner, Electrochemical Methods Fundamentals and Applications(2d ed. 2006), and Frank Endres, Douglas MacFarlane, & Andrew Abbott,Electrodeposition in Ionic Liquids (2008), each of which is incorporatedherein by reference in its entirety.

The present invention includes methods for directly depositingnanostructures comprising at least one LIB active material onto asubstrate via electrochemical deposition, as well as compositions,devices, and components related thereto, and methods and processes forforming such compositions, devices, and components.

With the direct electrochemical deposition methods of the presentinvention, LIB active materials can be simultaneously formed anddeposited onto the substrate. By “direct deposition” or “directelectrochemical deposition” of active materials, or active materials“deposited directly” or “electrochemically deposited directly,” as thoseterms are used herein, it is meant that the LIB active materials aregrown or formed by reduction of precursor materials directly on thedesired substrate surface via an electrochemical deposition process. Theactive material is reduced directly onto the substrate such that theactive material is formed in direct physical contact with the substrate.

The “active material” or “active materials,” as discussed herein, refersto one or more battery active materials—particularly LIB activematerials capable of being lithiated with Li ions and suitable for useas active materials in a LIB anode active material. The active materialscan include any suitable LIB active materials known in the art,including silicon (Si), graphite, carbon (C), tin (Sn), germanium (Ge),titanium (Ti), lead (Pb), indium (In), aluminum (Al), bismuth (Bi),antimony (Sb), lithium (Li), cobalt (Co), zinc (Zn) or other activematerials, as well as combinations, mixtures, intermetallic compounds,and alloys thereof. As referred to herein, “inactive material” or“inactive materials” refers to materials which are either incapable oflithium insertion or have negligible lithium insertion capacity comparedto the counterpart active material(s) in the LIB component formedaccording to the methods of the present invention. Inactive materialsmay be useful for purposes other than providing lithium capacity, suchas to provide increased conductivity, to improve adhesion between theactive material and the substrate, or to achieve certain characteristicsof the active material during or after the electrochemical depositionprocess, as discussed in further detail below. Inactive materials mayinclude, e.g., copper (Cu), carbon (C), nickel (Ni), silver (Ag),aluminum (Al), gold (Au), or other inactive materials, as well ascombinations, mixtures, and alloys thereof.

In preferred embodiments, an LIB active material is electrochemicallydeposited directly onto the substrate surface. The electrochemicallydeposited material can include a single active material; a mixture,composition, or alloy comprising multiple different active materials;one or more inactive materials; a mixture, composition or alloycomprising multiple inactive materials; or a mixture, composition, oralloy comprising one or more active materials and one or more inactivematerials. Additionally or alternatively, one or more active materialsand/or one or more inactive materials can be formed or deposited on thesubstrate via any suitable known methods, e.g., coating, chemicalbinding, adsorption, binder material adhesion, lithography, sputtering,chemical vapor deposition (CVD), evaporation, electroless deposition, orother methods, as will be understood by persons of ordinary skill in theart.

In preferred embodiments, the one or more active materials formed viadirect ECD includes silicon—preferably discrete silicon nanostructures,e.g., Si nanowires or Si nanospikes. Preferably, the silicon activematerial is electrochemically deposited directly onto one or more LIBactive materials and/or one or more conductive current collectors toform a silicon-based composite structure for use in a LIB anode.

In one preferred class of embodiments, one or more active materials,preferably one or more active materials comprising silicon, iselectrochemically deposited onto one or more conductive currentcollector structures which can be used as a current collector in a LIBanode. Preferably, the current collector comprises one or more copperstructures, e.g., a copper sheet, film, plate, foil, mesh, foam, sponge;powder or plurality of particles/fibers/sheets/flakes/wires which can bepacked, interwoven, adhered, or otherwise associated with one another;or any combination thereof. In preferred embodiments, silicon iselectrochemically deposited directly onto a copper current collector,and the Cu—Si composite material can form a LIB anode material, whereinthe copper is a conductive current collector and the silicon is anactive material for lithiation and delithiation during LIB charge anddischarge cycling.

In another preferred class of embodiments, a first active material iselectrochemically deposited directly onto at least a second activematerial to form a composite active material comprising the first andsecond active materials, suitable for use as a LIB anode activematerial. In preferred embodiments, a first active material comprisingsilicon is electrochemically deposited directly onto at least a secondactive material, wherein the second active material comprises one ormore graphite structures to form a silicon-graphite composite LIB anodematerial. The one or more graphite structures can include one or more ofa graphite sheet, film, plate, foil, powder, particles, or fibers;sheet, film, plate, mesh, foam, sponge; powder or plurality ofparticles/fibers/sheets/flakes which can be packed, interwoven adhered,or otherwise associated with one another; or any combination thereof.

In one class of embodiments, a first active material iselectrochemically deposited directly onto one or more substratescomprising at least one conductive current collector and/or at least onesecond active material. Preferably, the first active material comprisessilicon. Preferably, the first active material comprises nanostructures,e.g., nanowires. Each of the current collectors and second activematerials can include any suitable materials and structures describedherein, including one or more of a sheet, film, plate, foil, mesh, foam,sponge; powder or plurality of particles/fibers/sheets/flakes/wireswhich can be packed, interwoven, adhered, or otherwise associated withone another; or any combination thereof. Preferably, the one or moresubstrates includes a current collector comprising one or more copperstructures and/or a second active material comprising one or moregraphite structures. In one embodiment, a first active material iselectrochemically deposited directly onto at least one structurecomprising at least a second active material, wherein the at least onestructure comprising the second material is associated with at least onecurrent collector. The first active material can also be depositeddirectly onto the at least one current collector via electrochemicaldeposition. The current collector and second active material can becombined or associated with one another using any suitable processesknown to those of ordinary skill in the art. For example, the conductivecurrent collector material(s) and the second (or more) active materialcan be mechanically bound, mixed, stacked, layered, pressed, interwoven,chemically bound, adsorbed, alloyed, or adhered using one or moreadhesive binder materials; or the materials can be combined usingablation techniques, chemical deposition techniques such as ECD or CVD,evaporation, electroless deposition, adsorption, spraying, coating,lithography, sputtering, dipping, bonding, or other techniques. Thecurrent collector and second active material can be combined orassociated with one another prior to the electrochemical deposition ofthe first active material, during the electrochemical depositionprocess, after the first active material is electrochemically depositedonto the desired substrate, or any combination thereof.

LIB Active Materials

As mentioned above, the present invention includes methods for directlydepositing nanostructures comprising at least one LIB active materialonto a substrate via electrochemical deposition, as well ascompositions, devices, and components related thereto, and methods andprocesses for forming such compositions, devices, and components. Asmentioned above, the one or more active materials formed via direct ECDpreferably includes silicon, but is not limited thereto. Althoughembodiments of the present invention are described herein in detail withrespect to silicon active materials deposited via direct ECD, additionaland alternative active materials are included in the compositions,methods, components, and devices of present invention, as will beunderstood by persons of ordinary skill in the art. For example, the oneor more active materials formed via direct ECD can include Si, Cu, Ni,Sn, Ge, Ti, Pb, In, Al, Bi, Sb, Li, Co, Zn, or other active materials,as well as compositions, mixtures, intermetallic compounds, alloys, orcombinations thereof.

In preferred embodiments, a LIB active material is electrochemicallydeposited directly onto the substrate surface. The electrochemicallydeposited material can include a single active material; a mixture,composition, or alloy comprising multiple different active materials;one or more inactive materials; a mixture, composition or alloycomprising multiple inactive materials; or a mixture, composition, oralloy comprising one or more active materials and one or more inactivematerials. Additional materials, including one or more active materialsand/or one or more inactive materials, can be formed on or associatedwith the substrate via any suitable method, including suitable methodsavailable in the art (e.g., mechanical or chemical binding, mixing,stacking, layering, pressing, interweaving, adsorption, alloying,adhesive binding, chemical deposition such as ECD or CVD, lithography,spraying, coating, sputtering, evaporating, dipping, bonding, or othermethods).

In certain embodiments, the electrochemically deposited material cancomprise multiple different materials, e.g., multiple different activematerials, multiple different inactive materials, or a combination ofone or more active materials and one or more inactive materials. Forexample, the electrochemically deposited materials can include Si andCu, Si and Sn, Si and C, Si and graphite, Si and Li, Si and one or moretitanates, Si and Pb, Si and In, Si and Al, Si and Bi, Si and Sb, Sn andCu, Sn and C, Sn and graphite, Sn and Li, Sn and one or more titanates,Sn and Pb, Sn and In, Sn and Al, Sn and Bi, Sn and Sb, Cu and C, Cu andgraphite, Cu and Li, Cu and one or more titanates, Cu and Pb, Cu and In,Cu and Al, Cu and Bi, Cu and Sb, C and Cu, non-graphitic C and graphite,C and Li, C and one or more titanates, C and Pb, C and In, C and Al, Cand Bi, C and Sb; Si, Cu, and Sn; Si, Cu, and C; Si, Cu, and graphite;Si, Cu, and Li; Si, Cu, and one or more titanates; Si, Cu, and Pb; Si,Cu, and In; Si, Cu, and Al; Si, Cu, and Bi; Si, Cu, and Sb; Si, C, andSn; Si, C, and Cu; Si, C, and graphite; Si, C, and Li; Si, C, and one ormore titanates; Si, C, and Pb; Si, C, and In; Si, C, and Al; Si, C, andBi; Si, C, and Sb; Cu, C, and graphite; Cu, C, and Li; Cu, C, and one ormore titanates; Cu, C, and Pb; Cu, C, and In; Cu, C, and Al; Cu, C, andBi; Cu, C, and Sb; Si and Ni, Si and steel, Ni and steel, Ni and C, Cand steel, Sn and steel, Sn and Ni; Si, Sn, and Ni; Si, Sn, and steel;or compositions, mixtures, intermetallic compounds, alloys, orcombinations thereof.

In certain embodiments, nanostructures can be formed by ECD of one ormore alloy materials, co-deposition of multiple different materialsusing ECD (e.g., from the same EC electrolyte solution), or separate ECDof multiple different materials (e.g., alternating deposition ofmultiple different materials), as well as any combination thereof.Related processes and process parameters are described in further detailbelow.

Much to their surprise, the inventors of the present inventiondiscovered that the low-temperature, template-free, and catalyst-freeECD processes of the present invention could be used to achieveepitaxial growth of discrete active material nanostructures directly onone or more LIB components. Further, the inventors unexpectedlydiscovered that such ECD processes could be adjusted to finely controland/or modify the physical and chemical characteristics of theelectrochemically deposited nanostructures during the ECD growthprocess, including the composition, crystal structure, morphology, size,and/or shape of the active material nanostructures. ECD processes,materials, and additional parameters are explored in further detailbelow.

In preferred embodiments, the one or more active materials formed viadirect ECD comprise discrete nanostructures rather than a continuousactive material structure such as a continuous film comprising theactive material. By “discrete” structures, as such terminology is usedherein, it is meant that the structures include multiple independent anddiscontinuous domains of the material which forms, although suchstructures need not be entirely contiguous—i.e., “discrete” structuresmay physically contact one another unless otherwise specified. Thenanostructures can include essentially any desired type ofnanostructures, including, but not limited to, nanowires. Thenanostructures can comprise nanowires, nanorods, nanospikes, taperednanowires, nanotubes, nanowhiskers, nanoribbons, nanoparticles,nanofibers, nanocrystals, branched nanostructures, nanodots, quantumdots, spherical nanostructures, or other nanostructures, or anycombination thereof. Preferably, the nanostructures compriseone-dimensional, elongated, or high aspect ratio nanostructures. Forexample, the nanostructures can include nanowires, nanorods, nanospikes,tapered nanowires, nanotubes, nanowhiskers, nanoribbons, branchednanostructures, or other one-dimensional, elongated, or high aspectratio nanostructures, or any combination thereof. In preferredembodiments, the nanostructures comprise Si, e.g., Si nanowires. Morepreferably, the nanostructures comprise monocrystalline Sinanostructures, e.g., monocrystalline Si nanowires.

Preferably, the nanowires or other nanostructures of the presentinvention are formed as highly crystalline (e.g., highlymonocrystalline) nanostructures during the process of directelectrochemical deposition, such that no further processing is necessaryto crystallize the nanostructures. For example, the nanowires or othernanostructures preferably comprise monocrystalline Si and have a highdegree of crystallinity upon formation. The methods of the presentinvention allow for production of nanostructures which exhibit a highdegree of crystallinity upon formation during the ECD process. Suchimmediate crystallinity of the nanostructures upon deposition andformation eliminates the need for additional crystallization proceduressuch as high-temperature annealing. Thus, the entire process of formingthe active material nanostructures can be achieved using thelow-temperature, e.g., room temperature, ECD processes of the presentinvention.

Preferably, the nanowires or other nanostructures of the presentinvention are formed via ECD directly onto the desired substrate withoutthe use of a template. Such template-free deposition allows for highlycrystalline formation of the active material structures, whereas poroustemplate-based growth procedures disrupt continuous crystallineformation, thereby resulting in amorphous material formation. Intemplate-based methods, the electrochemically deposited material isconfined to the physical pores of the porous template, and the walls ofthe template pores prevent atoms of the material from depositing beyondthe pore boundaries, thereby preventing crystalline formation of thematerial. Thus, template-free ECD methods are preferred for forming theactive material nanostructures of the present invention. Template-freedeposition procedures of the present invention allow for the formationof active material nanostructures exhibiting a high degree ofcrystallinity, e.g., a high degree of monocrystallinity, a high degreeof polycrystallinity, or a high degree of mixed monocrystallinity andpolycrystallinity. As each successive atom of the active material isdeposited onto the substrate during preferred ECD processes of thepresent invention, nanostructures comprising the active material areformed epitaxially, according to the natural crystal structure of thematerial. In these preferred embodiments, the nanostructures exhibit ahigh degree of monocrystallinity without grain boundaries or othercrystal defects. In preferred embodiments, the present inventionincludes highly crystalline Si nanostructures, e.g., highly crystallineSi nanowires, and methods for forming such highly crystalline Sinanostructures. Advantageously, the ECD methods of the present inventionallow for growth of crystalline active material nanostructures such asSi nanowires without the use of a growth template. Although thecrystalline nanostructures may become amorphous or less crystalline uponcharge cycling in a LIB, the initial crystallinity of thesenanostructures allows for the one-dimensional structure of elongatednanostructures to be maintained throughout the LIB cycling. Further, thehighly crystalline active material nanostructures of the presentinvention exhibit high tolerance for fast charge-discharge rates,meaning that the crystalline nanostructures can undergo fast chargecycling while maintaining high capacity. In other words, LIB cells withthe highly crystalline nanostructures of the present invention (e.g.,crystalline Si nanowires) have a higher power density than amorphous orpolycrystalline active material nanostructures. Thus, the crystallinenanostructures of the present invention are highly advantageous for usein LIBs for high power applications.

Preferably, the nanostructures formed according to methods of thepresent invention comprise highly crystalline nanostructures, e.g.,highly monocrystalline nanostructures, e.g., highly monocrystalline Sinanowires or other nanostructures. In preferred embodiments, thenanostructures are substantially monocrystalline and substantially freeof polycrystalline and amorphous materials upon formation. Preferably,the nanostructures are free of polycrystalline and amorphous materialsupon formation. Highly crystalline nanostructures can be formed by ECDprocesses of the present invention, and active material nanostructureshaving a high degree of crystallinity upon formation are preferred forthe LIB active material nanostructures of the present invention. Forexample, the active material nanostructures of the present invention canexhibit 100% crystallinity upon formation, at least 99% crystallinityupon formation, at least 98% crystallinity upon formation, at least 97%crystallinity upon formation, at least 96% crystallinity upon formation,at least 95% crystallinity upon formation, at least 90% crystallinityupon formation, at least 85% crystallinity upon formation, at least 80%crystallinity upon formation, or at least 75% crystallinity uponformation; e.g., 100% monocrystallinity upon formation, at least 99%monocrystallinity upon formation, at least 98% monocrystallinity uponformation, at least 97% monocrystallinity upon formation, at least 96%monocrystallinity upon formation, at least 95% monocrystallinity uponformation, at least 90% monocrystallinity upon formation, at least 85%monocrystallinity upon formation, at least 80% monocrystallinity uponformation, or at least 75% monocrystallinity upon formation; 100%polycrystallinity upon formation, at least 99% polycrystallinity uponformation, at least 98% polycrystallinity upon formation, at least 97%polycrystallinity upon formation, at least 96% polycrystallinity uponformation, at least 95% polycrystallinity upon formation, at least 90%polycrystallinity upon formation, at least 85% polycrystallinity uponformation, at least 80% polycrystallinity upon formation, or at least75% polycrystallinity upon formation; or a high degree of crystallinitycomprising mixed monocrystallinity and polycrystallinity. Althoughcrystalline nanostructures are preferred, the active materialnanostructures of the present invention can comprise amorphousmaterials, a mixture of amorphous and polycrystalline materials, amixture of amorphous and monocrystalline materials, or a mixture ofamorphous, polycrystalline, and monocrystalline materials.

The nanowires or other nanostructures can be produced from any suitablematerial, including, but not limited to, silicon. In embodiments inwhich the nanostructures comprise silicon, the nanostructures cancomprise monocrystalline silicon, polycrystalline Si, amorphous Si, or acombination thereof. Thus, in one class of embodiments, thenanostructures comprise a monocrystalline core and a shell layer,wherein the shell layer comprises amorphous Si, polycrystalline Si, or acombination thereof. In one aspect, the nanostructures are Si nanowires.

The present invention includes low-temperature, e.g., room-temperature,ECD methods for producing active material nanostructures without the useof high-temperature CVD processes. Conventional methods for producingnanowires or other nanostructures, such as high-temperature catalyzedgrowth via CVD, require metal catalyst materials such as metal catalystparticles, whereby the metal catalyst is heated to a eutectictemperature to allow diffusion of the precursor material through themetal catalyst. Since the precursor diffuses through the metal catalystmaterial and is not consumed in the reaction, these conventional methodsyield nanostructures attached or strongly bonded to the metal catalyst,requiring further processing to remove the metal catalyst. Unlike suchconventional methods, production methods of the present invention do notrequire the use of catalysts such as metal catalyst particles. Thecatalyst-free production methods of the present invention allow forproduction of active material nanostructures and LIB active materialcomposite structures which are free of catalyst materials and impuritiesassociated therewith, eliminating the need for further processing toremove catalyst materials or impurities from the nanostructures. Thesecatalyst-free active material structures allow for LIBs and LIBcomponents having a reduced amount of inactive materials and thus,increased capacity and reduced weight and reduced volume.

In preferred methods, the ECD processes of the present invention includetemplate-free formation of active material nanostructures, e.g., Sinanowires, directly on LIB anode composite materials such as one or moreLIB current collectors and/or LIB active materials, e.g., one or morecopper current collectors and/or graphite active materials. Suchprocesses eliminate the need for a separate growth substrate and anon-conductive growth template, as well as the requirement of harvestingthe active material by dissolving or otherwise removing the growthsubstrate and template. Since the active material nanostructures areformed directly on LIB components or materials, the substrate and activematerial composite can be used as a LIB component without the need toremove the growth substrate or a growth template. Thus, the productionprocess is simplified. Further, impurities introduced by one or more ofthe separate growth substrate and template are eliminated.

In preferred embodiments, the active material nanostructures are free orsubstantially free of impurities, e.g., oxygen, including impuritiesintroduced by catalyst materials, growth templates, extraneous growthsubstrates, and procedures or materials used to remove such substancesfrom the active material nanostructures or composite structurescomprising the active material nanostructures. For example, the activematerial nanostructure composition includes less than 10% impurities,less than 9% impurities, less than 8% impurities, less than 7%impurities, less than 6% impurities, less than 5% impurities, less than4% impurities, less than 3% impurities, or less than 2% impurities;preferably less than 1% impurities, e.g., less than 0.5% impurities,less than 0.25% impurities, less than 0.1% impurities. Most preferably,the active material nanostructure composition is entirely free ofimpurities. Since neither high-temperature catalysis nor post-depositionannealing are required to form crystalline active materialnanostructures according to embodiments of the present invention, theinvention allows for epitaxial formation of highly crystalline activematerial nanostructures, wherein the entire formation process occurs atlow temperatures, e.g., room temperature.

The nanowires or other nanostructures of the present invention, e.g., Sinanowires, can be of essentially any desired size. For example, thenanowires or other nanostructures can have a diameter of about 10 nm toabout 500 nm, or about 20 nm to about 400 nm, about 20 nm to about 300nm, about 20 nm to about 200 nm, about 20 nm to about 100 nm, about 30nm to about 100 nm, or about 40 nm to about 100 nm. Preferably, thenanowires or other nanostructures have an average diameter less thanabout 150 nm, e.g., between about 10 nm and about 100 nm, e.g., betweenabout 30 nm and about 50 nm, e.g., between about 40 nm and about 45 nm.Preferably, the nanowires or other nanostructures have an average lengthless than about 100 μm, e.g., less than about 50 μm, less than about 10μm, about 100 nm to about 100 μm, or about 1 μm to about 75 μm, about 1μm to about 50 μm, or about 1 μm to about 20 μm in length. The aspectratios of the nanowires are optionally up to about 2000:1 or about1000:1. For example, the nanowires or other nanostructures can have adiameter of about 20 nm to about 200 nm and a length of about 0.1 μm toabout 50 μm.

As mentioned above, the discrete nanostructures formed by the ECDmethods of the present invention can include essentially any desiredtype of nanostructures, including, but not limited to, nanowires. Thenanostructures can comprise nanowires, nanorods, nanospikes, taperednanowires, nanotubes, nanowhiskers, nanoribbons, nanoparticles,nanofibers, nanocrystals, branched nanostructures, nanodots, quantumdots, spherical nanostructures, or other nanostructures, or anycombination thereof. Preferably, the nanostructures compriseone-dimensional, elongated, or high aspect ratio nanostructures. Forexample, the nanostructures can include nanowires, nanorods, nanospikes,tapered nanowires, nanotubes, nanowhiskers, nanoribbons, branchednanostructures, or other one-dimensional, elongated, or high aspectratio nanostructures, or any combination thereof. In preferredembodiments, the nanostructures comprise Si, e.g., Si nanowires, Sinanospikes, or tapered Si nanowires. More preferably, the nanostructurescomprise monocrystalline Si nanostructures, e.g., monocrystalline Sinanowires.

As explained in further detail below, the methods of the presentinvention allow for fine control and/or modification of physical andchemical characteristics of the electrochemically depositednanostructures during the ECD growth process, including the composition,crystal structure, morphology, size, and shape of the active materialnanostructures.

In certain embodiments, the electrochemically deposited nanostructureshave a porous structure. The porous structure can be achieved withlithiation-delithiation cycling, including pre-lithiation/delithiation(i.e., prior to LIB formation), as explained in detail below.

According to embodiments of the present invention, the physical and/orchemical characteristics of the nanostructures can be controlled, aswell as the interaction between the substrate surface and thenanostructures comprising at least one active material.

In preferred embodiments, the electrochemically deposited nanostructureshave a sufficiently high bond strength with the underlying substrate towhich the nanostructures are attached, whereby the bond between thesubstrate and nanostructures remains in tact during LIB charge anddischarge cycles. In preferred embodiments, the nanostructures aredirectly bound to the underlying substrate without a binder materialpositioned therebetween. In certain embodiments, a LIB anode includes acurrent collector and active material composite which does not include abinder material. For example, active material nanostructures (e.g., Sinanowires) can be formed directly on a LIB current collector structure(e.g., graphite foil or Cu film or mesh) via direct electrochemicaldeposition, whereby the current collector-active material composite doesnot include a binder material. The high bond strength between thesubstrate and the active material nanostructures eliminates the need fora binder. However, certain embodiments of the present invention caninclude a binder material between one or more active material structuresand/or inactive material structures.

In certain embodiments, as shown in FIGS. 2A-2F, elongatednanostructures 220, e.g., nanowires or nanospikes, are formed via directECD on a surface 216 of a substrate 215. Preferably, nanostructurescomprising Si, e.g., Si nanowires or Si nanospikes, are formed directlyon one or more of a current collector or another active materialstructure, e.g., a planar Cu current collector, a graphite film, or agraphite particle. The elongated nanostructures 220 can have a length,L₁, which represents the overall length taken along the long axis of thenanostructure. For example, the elongated nanostructures can includenanowires as shown in FIGS. 2A-2C, tapered nanowires as shown in FIG.2C, or nanospikes as shown in FIGS. 2D and 2F.

In preferred embodiments, the nanostructures exhibit both a high surfacearea for lithiation and a high surface area bound to the substrate. Incertain embodiments, as depicted in FIG. 2B, the elongatednanostructures 220 are in direct physical contact with the substratesurface 216 along a length, L₂, which is a portion of the overalllength, L₁, whereby L₂ is less than L₁. In certain embodiments, as shownin FIGS. 2A and 2C-2F, the nanostructures 220 are in direct physicalcontact with the substrate surface 216 along the end or base surface 216of the nanostructures. As shown in FIGS. 2C, 2D, and 2E, thenanostructures can have a base width, W₁, measured at the nanostructurebase 221 of the nanostructure 220 at the interface between thenanostructure 220 and the substrate 215; a center width, W₂, measured ata location 223 along the length of the long axis of the nanostructurewhich is approximately equidistant from the base end 221 and the distalend 222 of the nanostructure; and a distal width W₃ measured at thedistal end 222 of the nanostructure which is opposite the base end 221.In embodiments where the nanostructures have a circular cross-section(e.g., tapered nanowires or nanospikes), the aforementioned widths canrepresent the diameters of the nanostructure at the different respectivelocations along the long axis of the nanostructure. The base width, W₁,can be larger than the center width, W₂, larger than the distal width,W₃, or larger than both the center width and the distal width. As shownin FIGS. 2D and 2E, the base width, W1, can be substantially larger thanthe center width, W₂, and the distal width, W₃.

In certain embodiments, the discrete nanostructures comprising at leastone active material can comprise a plurality or cluster ofnanostructures, e.g., a cluster of elongated nanostructures such asnanowires or nanospikes. Each cluster can comprises a plurality ofelongated nanostructures conjoined at the base end of the cluster at theinterface between the cluster and the substrate surface. As shown in theexample embodiment of FIG. 2F, the discrete nanostructures includeclusters 225 of nanospikes 220, wherein each cluster 225 comprises aplurality of nanospikes 220 conjoined at the base end 221 of the clusterat the interface between the cluster 225 and the substrate surface 216.

In certain embodiments, the discrete nanostructures comprising at leastone active material can have one or more rounded surfaces, asillustrated in the example embodiments of FIGS. 2G-2K. As shown in FIG.2G, the nanostructures can comprise spherical nanostructures 220, e.g.,nanodots or spherical nanocrystals. The nanostructures can also includeellipsoid-shaped nanostructures or any other nanostructures having oneor more rounded surfaces. As shown in FIG. 2H, the nanostructures caninclude dome-shaped nanostructures 220 or hump-shaped nanostructures220. As shown in FIGS. 2I-2K, the nanostructures 220 can includemultiple rounded surfaces. As shown in FIGS. 2 i and 2J, thenanostructures 220 can have a lumpy surface structure. As shown in FIG.2K, the nanostructures 220 can be formed as discrete clusters 225,wherein each cluster 225 comprises multiple nanostructures 220 havingone or more rounded surfaces.

As described above, the nanostructures comprising at least one activematerial can comprise a single material type or multiple differentmaterial types. The nanostructures can include one or more activematerials, one or more inactive materials, or one or more conductivematerials, including any of the material compositions mentioned herein,as well as mixtures, alloys, or combinations thereof. Theelectrochemically deposited nanostructures can comprise heterostructurenanostructures formed via one or more ECD processes of the presentinvention. In certain embodiments, these structures can be formed by ECDof one or more alloy materials, co-deposition of multiple differentmaterials using ECD, or separate ECD of multiple different materials, aswell as any combination thereof. Related processes and processparameters are described in further detail below.

The example nanostructure embodiments of FIGS. 3A-3I show nanostructures320, each including different or varying material types throughoutdifferent portions (i.e., different spatial regions) of thenanostructure. As shown in FIG. 3A, the nanostructure 320 can comprise afirst region 330 comprising a first material M1 and at least a secondregion 332 comprising a second material M2, wherein the first materialM1 and the second material M2 are different. As explained above, each ofthe different materials can include a single material composition or amixture, alloy, or combination of multiple material compositions. Eachdifferent material type can include an active material, an inactivematerial, a conductive material, or any combination thereof. Forexample, M1 can include a first active material such as Si, and M2 caninclude a second active material such as Sn or graphite. M1 can includean active material such as Si, and M2 can include a conductive materialsuch as Cu, or vice versa. As shown in FIG. 3B, the nanostructure 220can comprise multiple first regions 330 comprising a first material M1and at least a second region 332 comprising at least a second materialM2, wherein the first material M1 and the second material M2 aredifferent, and wherein the second region 332 is disposed between themultiple first regions 330. As shown in FIGS. 3C-3E, each of thenanostructures 320 can comprise multiple first regions 330 comprising afirst material M1 and multiple second regions 332 comprising a secondmaterial M2, wherein the first material M1 and the second material M2are different. As shown in FIG. 3C, the first regions 330 and secondregions 332 can have an orderly pattern, e.g., an alternating pattern.Additionally or alternatively, as shown in FIGS. 3D-3E, the firstregions 330 and second regions 332 can have a random configuration. Incertain embodiments, the nanostructures can each comprise multipledifferent materials, wherein the different materials, wherein the amountor concentration of one or more of the different materials variesgradually across one or more regions of the nanostructure. For example,as shown in FIG. 3F, the nanostructures 320 can include a firstmaterial, M1, and at least a second material, M2, wherein the amounts orconcentrations of both M1 and M2 vary gradually across one or moreregions of the nanostructure. For example, as shown in FIG. 3F, in thenanostructures 320, the amount or concentration of the first material M1decreases gradually toward the distal end 322 of the nanostructure andincreases gradually toward the substrate surface 316, the amount orconcentration of the second material M2 increases gradually toward thedistal end 322 of the nanostructure and decreases gradually toward thesubstrate surface 316. In the nanostructure 320, the amount orconcentration of the first material M1 decreases gradually toward boththe substrate surface 316 and the distal end 322, whereas the amount orconcentration of the second material M2 increases gradually toward boththe substrate surface 316 and the distal end 322.

As shown in FIGS. 3G-3I, the nanostructures can include at least onecore and at least one coating or shell layer, wherein at least one corematerial differs from at least one coating material. For example, asshown in FIG. 3G, the nanostructure 320 comprises a core 335 comprisinga first material M1 and at least one coating layer 336 comprising asecond material M2, wherein M1 and M2 are different. As shown in FIG.3H, the core 335 comprises a first material M1, and the nanostructurecomprises multiple coatings or shell layers 336 a, 336 b. Thenanostructure includes a first shell 336 a comprising a second materialM2 and at least a second shell 336 b comprising a third material M3,wherein at least two of the materials M1, M2, and M3 are different. Asshown in FIG. 3I, the nanostructure 320 comprises a core comprising afirst region 335 a comprising a first material M1 and a second region335 b comprising a second material M2, wherein M1 and M2 are differentmaterials. The nanostructure 320 includes a shell 336 comprising a thirdmaterial M3, which can be the same as M1 or M2 or different than bothmaterials M1 and M2.

In certain embodiments, the nanowires or other nanostructures caninclude one or more coatings or shell layers formed over the individualnanostructures. The coatings or shell layers can include materialshaving a different crystalline structure than the core, one or more SEImaterials or layers, binder materials, a different active material thanthe core, a conductive material coating, or any other materials orcoatings.

In preferred embodiments, the nanostructures and the one or moresubstrate materials are formed into a LIB anode composite. In certainembodiments, the composite anode structure can have one or moreproperties which vary over different spatial regions of the composite.For example, the porosity, composition, or one or more othercharacteristics can very over different spatial regions of the compositeanode structure.

In preferred embodiments, the heterostructure nanostructures are formedby ECD onto the desired substrate. In certain embodiments, at least oneportion of the nanostructures are formed via ECD and at least oneportion of the nanostructures are formed using another method, e.g.,coating, chemical binding, adsorption, binder material adhesion,lithography, sputtering, chemical vapor deposition (CVD), evaporation,electroless deposition, or other methods available in the art, as willbe understood by persons of ordinary skill in the art. In one exampleembodiment, the discrete nanostructures comprise a first material, Mt,and at least a second material, M2, wherein the first material M1 isformed via ECD and the second material is formed by another method whichis not ECD. Preferably, M1 is an active material (e.g., Si) and M2 caninclude an active material (e.g., graphite or Sn) or an active materialwhich is less active or has a lower lithiation capacity than M1 (e.g.,M1 comprises SI and M2 comprises graphite). M2 can include an inactivematerial such as a binder (e.g., carboxylmethyl cellulose (CMC),polyvinylidene fluoride (PVDF), or polyacrylic acid (PAA), orpoly(acrylamide-co-diallyldimethylammonium) (PAADAA)), or an inactiveconductive material (e.g., Cu).

Substrate Materials and Structures

As mentioned above, the present invention includes methods for directlydepositing nanostructures comprising at least one LIB active materialonto a substrate via electrochemical deposition, as well ascompositions, devices, and components related thereto, and methods andprocesses for forming such compositions, devices, and components. Withthe direct electrochemical deposition methods of the present invention,LIB active materials can be simultaneously formed and deposited onto thesubstrate, whereby discrete nanostructures comprising one or more LIBactive materials are grown by reduction of precursor materials directlyon the desired substrate surface during the ECD process. The activematerial is reduced directly onto the substrate such that the activematerial nanostructures are in direct physical contact with thesubstrate. The discrete nanostructures can include any of thenanostructure characteristics described herein. In preferredembodiments, the discrete nanostructures comprise monocrystalline Si.Preferably, the discrete nanostructures include monocrystalline Sinanowires or nanospikes.

The substrate can include any conductive material. For example, thesubstrate can comprise one or more metals, copper (Cu), carbon (C),graphite, nickel (Ni), steel, aluminum (Al), platinum (Pt), gold (Au),tin (Sn), titanium (Ti), zinc (Zn), lithium (Li), inorganicsemiconductor materials, one or more conductive polymers; one or morebinder materials such as CMC, PVDF, PAA, or PAADAA; or other conductivematerials, as well as any composition, mixture, intermetallic compound,alloy, or combination thereof. In certain embodiments, the substrateincludes multiple materials, e.g., Cu and graphite, non-graphitic C andgraphite, Ni and graphite, steel and graphite, Al and graphite, Pt andgraphite, Cu and C, Cu and Sn, C and Sn, multiple forms of graphite,multiple forms of C; Cu, non-graphitic C, and graphite; graphite and oneor more binder materials, or any composition, mixture, alloy, orcombination thereof.

The one or more substrate materials can include any combination ofmaterials, crystal structures, crystallinity, morphology, shape, andsize. The substrate can include one or more of a conductive sheet, film,plate, foil, mesh, foam, sponge; or powder or plurality ofparticles/fibers/sheets/flakes/wires which can be packed, interwoven,adhered, or otherwise associated with one another; as well as anycombination thereof. In one general class of preferred embodiments, thesubstrate includes at least one porous substrate structure. In anothergeneral class of preferred embodiments, the substrate includes at leastone planar substrate structure. Preferably, the substrate includes atleast one metal or conductive planar structure. For example, thesubstrate can include one or more film, sheet, foil, mesh, planarsponge, plurality of particles, wires, or fibers formed into a planarshape or structure, or other planar structures, or any combinationthereof.

In one class of embodiments, a first active material iselectrochemically deposited directly onto one or more substrates,wherein the substrate comprises at least one conductive LIB currentcollector structure and/or at least one second active material.Preferably, the first active material comprises silicon. Preferably, thefirst active material comprises nanostructures, e.g., nanowires. Each ofthe current collectors and second active materials can include anysuitable materials and structures described herein, including one ormore of a sheet, film, plate, foil, mesh, foam, sponge; powder orplurality of particles/fibers/sheets/flakes/wires which can be packed,interwoven, adhered, or otherwise associated with one another; or anycombination thereof. Preferably, the one or more substrates includes acurrent collector comprising one or more copper structures and/or asecond active material comprising one or more graphite structures. Inone embodiment, a first active material is electrochemically depositeddirectly onto at least one structure comprising at least a second activematerial, wherein the at least one structure comprising the secondmaterial is associated with at least one current collector. The firstactive material can also be deposited directly onto the at least onecurrent collector via electrochemical deposition. The current collectorand second active material can be combined or associated with oneanother using any suitable processes known to those of ordinary skill inthe art. For example, the conductive current collector material(s) andthe second (or more) active material can be mechanically bound, mixed,stacked, layered, pressed, interwoven, chemically bound, adsorbed,alloyed, or adhered using one or more adhesive binder materials; or thematerials can be combined using ablation techniques, chemical depositiontechniques such as ECD or CVD, adsorption, spraying, coating,lithography, sputtering, dipping, bonding, or other techniques. Thecurrent collector and second active material can be combined orassociated with one another prior to the electrochemical deposition ofthe first active material, during the electrochemical depositionprocess, after the first active material is electrochemically depositedonto the desired substrate, or any combination thereof.

In preferred embodiments, an LIB active material is electrochemicallydeposited directly onto the substrate surface. The electrochemicallydeposited material can include a single active material; a mixture,composition, or alloy comprising multiple different active materials;one or more inactive materials; a mixture, composition or alloycomprising multiple inactive materials; or a mixture, composition, oralloy comprising one or more active materials and one or more inactivematerials. Additionally or alternatively, one or more active materialsand/or one or more inactive materials can be formed or deposited on thesubstrate via any suitable known methods, e.g., coating, chemicalbinding, adsorption, binder material adhesion, lithography, sputtering,chemical vapor deposition (CVD), or other methods, as will be understoodby persons of ordinary skill in the art. Exemplary substrates includeone or more of the following: graphite foil or plate, polished graphitefoil or plate, graphite flakes or particles, graphite flakes orparticles and one or more binder materials such as CMC, PVDF, PAA, orPAADAA, graphite flakes or particles combined with one or more bindermaterials and coated on graphite foil or plate, Cu-coated graphite foil,Cu-coated graphite foil coated with graphite flakes or particles,graphite flakes or particles combined with one or more binder materialsand coated on a Cu-coated graphite foil or plate, Cu-coated graphitefoil or plate subjected to gas treatment, porous Cu mesh or foam, Cuwires, Cu fibers, Ni-coated Cu wires or fibers, patterned Cu wires,Ni-coated patterned Cu wires, carbon sheet, heat-treated carbon sheet,Cu foil or plate coated with graphite flakes or particles, graphiteflakes or particles combined with one or more binder materials andcoated on a Cu foil or plate, graphite flakes or particles disposedbetween or pocketed by porous Cu mesh sheets, graphite flakes orparticles combined with one or more binder materials and disposedbetween or pocketed by porous Cu mesh sheets, one or more bindermaterials such as CMC, PVDF, PAA, or PAADAA, and combinations thereof.In certain embodiments, the substrate can be gas treated with one ormore reductant gases to allow for increased reduction of metallic ionsonto the substrate surface. In certain embodiments, the substratesurface can be heat-treated. For example, the substrate can compriseheat-treated carbon, wherein the heat treatment creates graphiticfeatures on the surface of the carbon substrate structure.

In one general class of embodiments, the ECD substrate comprises carbon.The substrate can comprise one or more carbon structures. The carbonsubstrate structures can comprise any suitable form of carbon, includinggraphite, graphene, natural graphite, artificial graphite,highly-ordered pyrolitic graphite (HOPG), activated carbon, petroleumcoke carbon, mesophase carbon, hard carbon, soft carbon, carbon black,porous carbon, fullerenes, heat-treated carbon, or other forms ofcarbon, as well as combinations thereof. The carbon substrate structurescan comprise carbon film or foil, carbon sheets, carbon paper, carbonpowder, porous carbon powder, carbon fibers, carbon particles, carbonmicrobeads, mesocarbon microbeads (MCMB), carbon nanotubes, carbonnanoparticles, graphite fibers, graphite particles or powder, graphitefoil, or other carbon structures, as well as combinations thereof.

In another general class of embodiments, the ECD substrate comprisescopper. The substrate can comprise one or more copper structures. Forexample, the substrate can include one or more copper film, foil, plate,or sheet; copper mesh, foam, or sponge; copper wires, interwoven copperwires, copper particles, copper flakes; one or more layers of coppercoated on another substrate material such as a graphite foil, carbonpaper, or graphite particles; or other copper structures, as well ascombinations thereof.

In preferred embodiments, the substrate comprises one or more conductivecurrent collector structures and/or one or more LIB active materialstructures, whereby the one or more substrate materials and the discretenanostructures comprising at least one active material form a compositestructure for use in a LIB anode. For example, the nanostructures can beformed directly on a current collector structure to form an anodecurrent collector comprising the discrete active materialnanostructures. The anode current collector structure can include anactive material (e.g., graphite) and/or an inactive material (e.g., Cu).

In one general class of embodiments, the nanostructures comprising afirst active material (e.g., Si) can be formed directly on one or morestructures comprising a second active material (e.g., graphite),resulting in a composite active material structure comprising the firstand second active material. The composite structure comprising the firstand second active material can be associated with a current collectorstructure, e.g., a Cu current collector. For example, the compositestructure comprising the first and second active material can beassociated with the current collector material after formation of thecomposite structure. In other embodiments, the substrate structurecomprising the second active material can be associated with a currentcollector substrate prior to the formation of the discretenanostructures thereon. In other embodiments, the substrate structurecomprising the second active material can be associated with a currentcollector substrate simultaneously with formation of the discretenanostructures thereon. For example, the second active material and thediscrete nanostructures comprising the first active material can beco-deposited onto the current collector substrate structure.

The one or more substrates can include a LIB anode active material, aLIB anode current collector, or both an active material and a currentcollector. Upon ECD of LIB active material nanostructures onto the LIBanode active material and/or current collector substrate structure(s),the resulting composite is preferably included as an anode component ina LIB. In preferred embodiments, the active material iselectrochemically deposited onto one or more substrates including LIBcurrent collectors and/or additional anode active materials. The currentcollector can comprise copper, a copper plate, copper mesh, coppersponge, carbon, or carbon paper. The active materials can includegraphite, including graphite particles or graphite powder. In one classof preferred embodiments, the substrate includes a LIB current collectorincluding carbon, copper, or a combination thereof. The substrate caninclude copper materials such as a copper plate, mesh, or sponge.Additionally or alternatively, the substrate can include carbon-basedmaterials such as carbon paper or graphite, including graphite powder ora plurality of graphite particles. The substrate may also include acombination of materials such as copper and carbon, copper and graphite,or graphite and non-graphitic carbon. For example, the copper iselectrochemically deposited onto graphite particles to form asilicon-graphite composite LIB anode material. In another class ofpreferred embodiments, the substrate includes LIB active materialsincluding graphite, preferably a plurality of graphite particles, morepreferably fine graphite powder or flakes.

In one preferred class of embodiments, one or more activematerials—preferably one or more active materials comprising silicon, iselectrochemically deposited onto one or more conductive currentcollector structures which can be used as a current collector in a LIBanode. Preferably, the current collector comprises one or more copperstructures, e.g., a copper sheet, film, plate, foil, mesh, foam, sponge;powder or plurality of particles/fibers/sheets/flakes/wires which can bepacked, interwoven, adhered, or otherwise associated with one another;or any combination thereof. In preferred embodiments, silicon iselectrochemically deposited directly onto a copper current collector,and the Cu—Si composite material can form a LIB anode material, whereinthe copper is a conductive current collector and the silicon is anactive material for lithiation and delithiation during LIB charge anddischarge cycling.

In another preferred class of embodiments, a first active material iselectrochemically deposited directly onto at least a second activematerial to form a composite active material comprising the first andsecond active materials, wherein the composite active material structureis suitable for use as a LIB anode active material. In preferredembodiments, a first active material comprising silicon iselectrochemically deposited directly onto at least a second activematerial, wherein the second active material comprises one or moregraphite structures to form a silicon-graphite composite LIB anodematerial. The one or more graphite structures can include one or more ofa graphite sheet, film, plate, foil, powder, particles, or fibers;sheet, film, plate, mesh, foam, sponge; powder or plurality ofparticles/fibers/sheets/flakes which can be packed, interwoven adhered,or otherwise associated with one another; or any combination thereof.

In one general class of embodiments, silicon nanostructures, e.g., Sinanowires, are formed via direct electrochemical deposition on aplurality of graphite particles, preferably graphite microparticles. Thegraphite particles comprising silicon nanoparticles deposited thereonare combined to form a porous, three-dimensional silicon-graphitecomposite anode active material. In another general class ofembodiments, silicon nanostructures, Si nanowires, are formed via directelectrochemical deposition on a plurality of distinct, individualcurrent collectors. For example, the current collectors can include aplurality of carbon and/or copper sheets, preferably porous sheetscomprising copper, such as mesh sheets or sponge sheets. The pluralityof current collectors can be combined to form a LIB component,preferably a current collector and active material composite anodecomponent. The plurality of current collectors can be combined in anysuitable manner to form the component, and the configuration of thecurrent collectors can be tailored to meet the structural requirementsof any particular battery system, as will be understood by persons ofordinary skill in the art. In one example class of embodiments, the LIBcomponent comprises a stack of multiple sheets comprising the conductivematerial and active material composite. Preferably, one or more of thesheets in the stack are porous, e.g., conductive mesh or sponge sheetshaving the active material deposited thereon. One or more of the sheetsin the stack can be non-porous or less porous than other sheets. Forexample, the sheets can have increasing porosity with increasingdistance from a bottom anode current collector sheet.

In preferred embodiments, the substrate comprises at least one graphitestructure, e.g., one or more graphite foil, film, or sheet structures;graphite powder, flakes, or particles; packed graphitepowder/flakes/particles, interwoven graphite powder/flakes/particles,graphite powder/flakes/particles adhered together with one or morebinder materials (e.g., CMC, PVDF, PAA, or PAADAA), other graphitestructures, or any combination thereof. The oen or more graphitestructures can include natural graphite, synthetic graphite, MCMB, HOPG,graphite powder, porous graphite, porous graphite film or graphite felt,heat-treated carbon having a graphitic surface, or other forms ofgraphite. Preferably, the one or more graphite structures includes anatural graphite surface. In certain embodiments, a graphite layer canbe formed on one or more other materials, e.g., non-graphitic carbon. Inpreferred embodiments, the substrate includes graphite foil or syntheticgraphite (e.g., synthetic graphite powder) coated on graphite foil.

In embodiments of the present invention which include a graphite film orfoil substrate structure, the graphite film or foil substrate can beused as a LIB anode active material, a LIB anode current collector, orboth an active material and a current collector. The graphite film orfoil substrate can be stacked on, adhered to, or otherwise combined withanother current collector structure, e.g., a Cu foil or film structure.In embodiments of the present invention, the graphite film or foilsubstrate, or a portion or one or more layers thereof, can be removedfrom the composite structure formed via one or more ECD processes of thepresent invention. This allows for minimization of the thickness of thegraphite layer while allowing the electrochemically deposited activematerial to remain in tact. The graphite foil substrate, or portions orone or more layers thereof, can be removed using methods available inthe art, e.g., peeling, rubbing, etching, scraping, dissolving, orapplying shear force to the graphite foil. In preferred embodiments, thegraphite film or foil substrate has a thickness of about 1 μm to about100 μm, preferably about 1 μm to about 50 μm, 1 μm to 50 μm, about 1 μmto about 25 μm, or 1 μm to 25 μm.

In one preferred class of embodiments, the ECD substrate comprisesgraphite powder including a plurality of graphite particles or flakes.The graphite particles preferably have an average size of about 1 μm toabout 100 μm, 1 μm to 100 μm, about 1 μm to about 50 μm, 1 μm to 50 μm,about 1 μm to about 50 μm, 1 μm to 50 μm, or preferably about 5 μm toabout 30 μm, or 5 μm to 30 μm.

Graphite powder or binder-graphite powder composite can be coated on,formed on, or otherwise associated with another substrate structure(e.g., graphite foil, Cu film, Cu mesh, Cu sponge). The graphite powderor binder-powder composite can be associated with a porous substrate.For example, the graphite powder can be packed into a pocket formed inor on the substrate structure. In another embodiment, the graphite isdisposed between two or more structures, wherein at least one of thestructures is porous or permeable so as to allow for the active materialto pass therethrough and deposit onto the graphite powder during the ECDprocess.

The graphite powder or binder-graphite powder composite can be formedinto a layer and optionally coated onto another substrate/scaffoldstructure. Preferably, the graphite-binder layer has a thickness ofabout 1 μm to about 200 μm, 1 μm to 200 μm, about 1 μm to about 100 μm,1 μm to 100 μm, about 1 μm to about 50 μm, or 1 μm to 50 μm. Preferably,the graphite powder layer or binder-powder layer is a porous layer.Preferably, the graphite-binder layer has a porosity of about 10%-70%.The graphite powder or binder-powder layer can have a varied porosity orconcentration over different spatial regions of the layer. For example,graphite powder layer can have lower porosity in the internal region ofthe layer and higher porosity near one or more external surfaces of thelayer. When coated on an electrode, a current collector, or anotherstructure, the graphite powder layer can have a lower porosity near theinterface and increasing porosity with increasing distance from theinterface between the graphite powder layer and the structure.Alternatively, the porosity can be higher at the interface and decreasewith increasing distance from the interface. Other features of thegraphite layer can also be varied over spatial regions of the graphitepowder layer, including graphite particle size, graphite particleconcentration, or binder concentration. For example, the binderconcentration can be higher near an interface between the graphitepowder layer and another structure, and the graphite powder layer canhave decreasing binder concentration with increasing distance from theinterface.

In one example embodiment, the substrate comprises graphite foil such asthe bare graphite foil depicted in FIGS. 4A-4D, showing scanningelectron microscope (SEM) images of the graphite foil surface atmagnifications of 300×, 1000×, 1500×, and 3000×, respectively. Thegraphite foil substrate can be used as both a substrate for the activematerial nanostructures and/or a LIB current collector structure. Inother embodiments, the graphite foil is a current collector and asubstrate/scaffold for deposition of one or more ECD substrate materials(e.g., graphite powder or Cu).

In one general class of embodiments, LIB active material nanostructures(e.g., Si nanowires or other nanostructures) are formed directly on agraphite foil substrate according to one or more direct ECD methods ofthe present invention.

FIGS. 5A-5C show photographs of various composite LIB anode structures,each comprising a graphite foil current collector substrate 215 anddiscrete Si nanostructures formed directly on the graphite foilaccording to various ECD methods of the present invention. As can beseen in FIGS. 5A-5C the bottom portion 538 of the graphite foil 515 wassubjected to an ECD process according to an embodiment of the presentinvention, resulting in the formation of at least one layer 540comprising discrete Si nanostructures formed directly on the graphitefoil substrate 515. Although FIGS. 5A-5C depict the layer 540 comprisingdiscrete active material nanostructures formed only on the bottomportion 538 of the graphite foil substrate 515, the layer 540 can beformed over the entire surface or any select portion of the substratesurface. This general concept applies to each of the embodiments of thepresent invention described herein, e.g., the embodiments shown in FIGS.5A-5C, 23, 26A-26B, 27A-27B, 38, 39, and 40. As can be seen in the SEMimages of FIGS. 6-22, discrete Si active material nanostructures areformed on the graphite foil substrate. As explained in further detailbelow, the ECD process parameters will affect the characteristics of theelectrochemically deposited material. The ECD processes corresponding tothe example embodiments of FIGS. 6-22 are described in further detailbelow. In preferred embodiments, the composite LIB anode structurecomprises elongated Si nanostructures formed via ECD directly on thesubstrate. For example, as shown in the example embodiments depicted inFIGS. 6A, 6B, 8A-12C, and 14A-14C, Si nanowires 520 can be deposited onthe substrate according to various direct ECD methods of the presentinvention. Additional active material nanostructures are also includedin the methods and compositions of the present invention, including thevarious active material nanostructures described herein. The discreteactive material nanostructures preferably include crystalline Si, e.g.,crystalline Si nanowires. However, active material nanostructurescomprising additional forms of Si are also included in the presentinvention. For example, the active material nanostructures can includeamorphous Si structures, polycrystalline Si structures, both amorphousand polycrystalline Si structures, or a nanostructures comprising acombination of crystalline Si and amorphous and/or polycrystalline Si.

In another general class of embodiments, LIB active materialnanostructures (e.g., Si nanowires or other nanostructures) are formeddirectly on a first substrate comprising graphite powder, or a pluralityof graphite particles, according to one or more direct ECD methods ofthe present invention. The ECD substrate comprising graphite powder, ora plurality of graphite particles, can be coated on or otherwiseassociated with a second substrate or scaffold structure such as agraphite foil structure, a Cu film or mesh structure, or a combinationthereof. Preferably, the ECD substrate comprises graphite powderincluding a plurality of graphite particles, graphite flakes, roundedgraphite particles, or spherical graphite particles. Discretenanostructures comprising at least one active material can beelectrochemically deposited on the graphite particles to form acomposite LIB anode active material structure.

In certain embodiments, the graphite particles are not bound togetherduring the ECD process. In other embodiments, the graphite powdersubstrate includes multiple groups of graphite particles bound together,wherein one or more of the groups of graphite particles form discretegroups of graphite particles—i.e., the groups are physically separatedfrom another during the ECD process. In certain embodiments, thegraphite particles are provided on another substrate structure such as aconductive plate, film, or sheet. For example, the first substratematerial comprising individual graphite particles or discrete groups ofgraphite particles can be provided on a second substrate (e.g., agraphite foil, Cu film, or porous Cu substrate/scaffold), whereby thediscrete graphite particles or the discrete groups of graphite particlesform discrete protrusions or surface features on the surface of thesecond substrate structure. The discrete protrusions or surface featuresare spatially separated from one another such that collectively, theplurality of discrete surface features (each comprising at least onegraphite particle) provide roughness on the second substrate surface.

In certain embodiments of the present invention, the graphite particlesof the graphite powder substrate can be physically associated with oneanother (e.g., bound or adhered together). The graphite particles can bephysically associated with one another before, after, or during the ECDprocess. In preferred embodiments, the graphite particles are boundtogether using one or more adhesive binder materials to form a graphitepowder and binder composite structure. Preferably, the binder includescarboxylmethyl cellulose (CMC), polyvinylidene fluoride (PVDF),poly(acrylamide-co-diallyldimethylammonium) (PAADAA), or polyacrylicacid (PAA). The graphite powder/particles can be combined with one ormore binder materials and coated onto a scaffold or substrate structuresuch as a planar conductive material structure, a graphite foilstructure, a Cu film structure, a Cu mesh or sponge structure, or acombination thereof. The binder and graphite powder can be depositedonto the scaffold/substrate using any suitable coating or depositionmethod, including battery slurry coating methods available in the art,including those described in U.S. patent application Ser. No.12/783,243, the entirety of which is incorporated herein by reference.Preferably, the planar scaffold/substrate comprises a porous layercomprising the graphite powder ECD substrate, a binder-graphite powdercomposite, a composite material comprising the graphite powder havingthe active material nanostructures formed thereon, or a compositematerial comprising the binder and the graphite powder having thediscrete nanostructures formed thereon. In one class of embodiments, thegraphite powder can be deposited on the scaffold/substrate prior to theECD process, whereby the planar scaffold/substrate and the graphitepowder form a composite substrate structure onto which thenanostructures are deposited via direct ECD. The discrete activematerial nanostructures can be directly deposited via ECD onto thegraphite particles or onto both the graphite particles and the planarscaffold/substrate. In other embodiments, the discrete active materialnanostructures are deposited onto the graphite powder/particles to forman active material composite, and the graphite powder/particlescomprising the nanostructures can be subsequently bound together andcoated onto the planar scaffold/substrate, e.g., using one or moreadhesive binder materials. As will be understood by persons of ordinaryskill in the art, the composite material can be coated onto thescaffold/substrate using conventional methods for coating a batteryslurry composite onto a substrate.

As can be seen in FIG. 23, the porous layer 2340 is formed on the lowerportion 2338 of the graphite foil substrate 2315. However, according tothe present invention, the layer 2340 can be formed over the entiresurface or a select portion of the graphite foil 2315 a. FIGS. 24A-24Cinclude SEM images of the porous layer 2340 at magnifications of 500×,2000×, and 5000×, respectively. In FIGS. 24A-24C, the porous layer 2340is shown prior to the direct ECD process—i.e., before the discreteactive material nanostructures are formed on the graphite particles 2415b. FIGS. 25A-25D include SEM images of a porous layer 2340 comprisinggraphite particles 2515 b after direct ECD of Si active materialnanostructures 2520 onto the graphite particles 2515 b. As can be seenin the images of FIGS. 25A-25D, discrete Si nanowires 2520 are formeddirectly on the graphite particles 2515 b via direct ECD according tomethods of the present invention. The discrete active materialnanostructures preferably include crystalline Si, e.g., crystalline Sinanowires. However, active material nanostructures comprising additionalforms of Si are also included in the present invention. For example, theactive material nanostructures can include amorphous Si structures,polycrystalline Si structures, both amorphous and polycrystalline Sistructures, or a nanostructures comprising a combination of crystallineSi and amorphous and/or polycrystalline Si.

In one example embodiment, a porous layer comprising graphitepowder/particles and an adhesive binder material is formed on a graphitefoil substrate/scaffold structure, and discrete Si nanostructures areformed on the graphite particles according to one or more direct ECDmethods of the present invention. The ECD process of this exampleembodiment is described in further detail below. The graphite powdersubstrate material 2315 b is coated on a graphite foil substratestructure 2315 a to create a composite graphite foil-graphite powdersubstrate for ECD of one or more active material nanostructures thereon.The graphite powder can be coated directly on the graphite foil. Incertain embodiments, the graphite powder can be coated on the graphitefoil or another substrate structure without the use of a bindermaterial. In preferred embodiments, the graphite foil is combined withat least one binder material (preferably CMC) and coated on the graphitefoil using conventional LIB slurry coating techniques. FIG. 23 shows aphotograph of a composite anode structure 2350 comprising a graphitefoil current collector 2315 a and a porous layer 2340 formed thereon,prior to Si deposition. After the ECD process wherein Si nanostructuresare formed on the graphite powder, the porous layer 2340 comprisesgraphite powder, a CMC binder material, and discrete Si nanostructuresformed on the graphite powder. As can be seen in FIG. 23, the porouslayer 2340 is formed on the graphite foil 2315 a at the bottom portion2338, which was subjected to the ECD process. FIGS. 24A-24C include SEMimages of the porous layer 2340 at magnifications of 500×, 2000×, and5000×, respectively. In FIGS. 24A-24C, the porous layer 2340 is shownprior to the direct ECD process—i.e., before the discrete activematerial nanostructures are formed on the graphite particles 2415 b.FIGS. 25A-25D include SEM images of a porous layer 2340 comprisinggraphite particles 2515 b after direct ECD of Si active materialnanostructures 2520 onto the graphite particles 2515 b. As can be seenin the images of FIGS. 25A-25D, discrete Si nanowires 2520 are formeddirectly on the graphite particles 2515 b via direct ECD according tomethods of the present invention. ECD processes of the present inventionare described in further detail below. Upon formation of a LIB anode,the graphite foil 2515 a and graphite powder 2515 b coating can be usedas current collector materials in a LIB, and the Si nanostructures canbe used as the active materials in a LIB. The graphite foil can alsocontribute to the active material of the LIB.

In another class of embodiments, the ECD substrate includes graphitepowder which is physically associated with a Cu substrate/scaffoldstructure, and discrete Si nanostructures are formed on the graphiteparticles according to one or more direct ECD methods of the presentinvention. Preferably, the Cu substrate structure includes a porous Custructure such as a porous Cu film or a Cu mesh or sponge structure.Preferably, the Cu substrate structure, e.g., a planar Cu structure, isboth a LIB current collector structure and a working electrode of theelectrochemical cell used in the ECD process. The graphite particles canbe deposited on one or more surfaces of the Cu structure, depositedwithin the pores of the porous Cu structure, disposed in a pocket formedby the Cu substrate, disposed between two or more sides of a folded Cusubstrate structure, disposed or sandwiched between multiple Cusubstrate structures, or any combination thereof. Preferably, the porousCu substrate (e.g., porous Cu mesh or sponge) has a porosity of about10-80%, about 10-50%, or about 10-30%, preferably about 30% or 30%. Asdescribed previously, the graphite particles can be deposited with orwithout a binder material, and the graphite powder can be arranged toprovide protrusions or surface features on one or more surfaces of theCu substrate.

In one example embodiment, as shown in FIGS. 26A-27B, the ECD substrateincludes graphite powder 2615 b, 2715 b. The graphite powder isphysically associated with the porous Cu substrate/scaffold structure2615 a, 2715 a, forming a graphite powder coating on at least onesurface of the Cu structure, and discrete Si nanostructures are formedon the graphite particles according to one or more direct ECD methods ofthe present invention. In this example, the graphite powder wasdeposited without a binder material, although one or more bindermaterials can be included to adhere the graphite particles to oneanother or to the Cu substrate. An example of a porous Cusubstrate/scaffold structure is shown in the optical microscope image ofFIG. 28 which shows the porous Cu material before the addition ofgraphite or other materials. FIGS. 26A-27B include photographs of theresulting LIB anode composite structure 2650, 2750 comprising a porousCu current collector, a graphite powder active material, and Si activematerial nanostructures on the graphite powder particles. FIGS. 30A-30Dand 31A-31D show SEM photos of Si active material nanostructures 3020,3120 deposited directly on the graphite particles disposed within theporous Cu substrate scaffold. During the direct ECD process of thisexample embodiment, the graphite powder substrate was disposed betweentwo surfaces of a porous Cu mesh electrode structure. FIGS. 30A-30D showthe Si-coated graphite particles which were disposed in the middle ofthe composite, while FIGS. 31A-31D show the Si-coated graphite particleswhich were disposed toward the outer surface of the composite (i.e.,closer to the porous Cu substrate scaffold). Heavier Si deposition wasachieved on the graphite particles on the outer region of the composite,as shown in FIGS. 31A-31D. As can be seen in FIGS. 29 and 32A-32D, LIBactive material nanostructures 3220 comprising Si were electrochemicallydeposited directly onto the porous graphite structure according to oneor more ECD methods of the present invention. The ECD process of thisexample embodiment is described in further detail below.

In yet another embodiment, as shown in FIG. 33, a Cu substrate material3315 b is coated on a graphite foil substrate structure 3315 a to createa composite graphite foil-Cu substrate for ECD of one or more activematerial nanostructures thereon. The Cu can be coated directly on thegraphite foil using conventional metal coating techniques such as ECD orevaporation. FIG. 33 shows the Cu-coated graphite foil substrate priorto Si deposition, and FIGS. 34 and 35 show two different samples ofsubstrates similar to the substrate shown in FIG. 33, with Sinanostructures formed thereon using one or more ECD processes of thepresent invention. Upon formation of a LIB anode, the graphite foil 3315a and Cu coating 3315 b can be used as current collector materials in aLIB, and the Si nanostructures can be used as the active materials in aLIB. The graphite foil can also contribute to the active material of theLIB. FIGS. 36A-36C show SEM photos of the Si-coated Cu of the structureshown in FIG. 34, and FIGS. 37A-37C show SEM photos of the Si-coated Cuof the structure shown in FIG. 35. The ECD process of this exampleembodiment is described in further detail below.

Multi-Material or Multi-Structure Substrates

In one general class of preferred embodiments of the present invention,a LIB anode comprises a multi-component or multi-material substratehaving high-capacity active material nanostructures, e.g. Sinanostructures, formed on one or more of the multiple substratecomponents and/or materials.

In one class of embodiments, the LIB active materials areelectrochemically deposited onto a first substrate, wherein the firstsubstrate is physically associated with a second substrate, wherein thefirst substrate and the second substrate have comprise one or moredifferent materials, shapes, sizes, morphologies, or othercharacteristics. The nanostructures can be electrochemically depositedon the first substrate before the first and second substrates arephysically associated with one another, as well as afterward orsimultaneously. A LIB anode component can be formed, wherein the anodecomponent comprises the second substrate, the first substrate, and theactive material nanostructures formed on the first substrate.

In another class of embodiments, the LIB active materials areelectrochemically deposited onto a substrate, wherein the substratecomprises a first substrate component and a second substrate component,wherein the first and second components comprise one or more differentmaterials, shapes, sizes, morphologies, or other characteristics. Theactive material nanostructures can be electrochemically deposited ontothe first material only, the second material only, or both the first andthe second material. A LIB anode component can be formed, wherein theanode component comprises the composite substrate and the activematerial nanostructures formed thereon.

In another class of embodiments, active material nanostructures areelectrochemically deposited on a plurality of substrates or a pluralityof substrate layers to form a three-dimensional LIB anode compositestructure. The plurality of substrates, or the plurality of substratelayers, and the active material nanostructures electrochemicallydeposited thereon are combined to form a three-dimensional LIB anodestructure which includes a mixture of the substrates and the activematerial nanostructures throughout a majority of the LIB anodethickness, t. The substrates can be electrochemically deposited on thesubstrates before the plurality of substrates are combined, as well asafterward or simultaneously. By way of example only, the plurality ofsubstrates can include a plurality of particle substrates, a pluralityof fiber substrates, a plurality of flake substrates, a plurality ofplanar substrate layers, at least one planar substrate layer and aplurality of particles, graphite particles, one or more graphite foillayers, one or more Cu film layers, one or more porous Cu structures,one or more carbon sheets or foils, or a combination thereof. As shownin the example embodiment of FIG. 38A, the substrates include aplurality of particles 3815 b having active material nanostructures 3820formed thereon. Preferably, the particles comprise graphite particles.The anode structure can have a porosity which decreases from the top3850 a to the bottom 3850 b of the anode structure, thereby allowing foruniform flow of the LIB electrolyte throughout the thickness, t, of theLIB anode structure. For example, the size of the graphite particles3815 b can decrease from top 3850 a to bottom 3850 b of the anodestructure, and/or the particles 3815 b can be more closely packed towardthe bottom 3850 b of the anode structure. As shown in the exampleembodiment of FIG. 38B, the LIB composite anode structure comprises aplurality of substrate layers 3815 a having active materialnanostructures 3820 electrochemically deposited on one or more surfacesof each layer. The bottom substrate layer can be a solid conductive filmor a porous structure. Preferably, the top substrate layers 3815 a eachcomprise a porous substrate layer. In one embodiment, the porosity ofthe layers 3815 a decreases from the top 3850 a of the anode structureto the bottom 3850 b of the anode structure—i.e., each of the top layersis more porous than the underlying substrate layers. As shown in FIG.38C, the LIB composite anode structure comprises at least one layerplurality of graphite particle substrates 3815 b disposed betweensubstrate layers 3815, wherein each of the particles 3815 b and layers3815 a comprise active material nanostructures formed thereon. One ormore of the layers 3815 a can comprise a porous structure. The porosityof the composite can decrease from top 3850 a to bottom 3850 b of theanode structure.

In preferred embodiments, the ECD substrate has an overall thickness ofabout 500 μm or less, 500 μm or less, about 300 μm or less, 300 μm orless, about 100 μm or less, preferably 100 μm or less or less than 100μm. Most preferably, substrate has a thickness of about 5-300 μm, mostpreferably about 5-100 μm. In preferred embodiments, the substrate andactive material nanostructures formed thereon comprise a composite LIBanode structure. Preferably, the composite LIB anode structure is thinenough to allow for easy and proper formation into a LIB device, e.g., acylindrical LIB cell structures. Most preferably, the composite LIBanode structure, including the substrate and the active materialnanostructures formed directly thereon, has an overall thickness of 100μm or less, preferably less than 100 μm.

Substrate Surface Modification and Surface Features

The substrate surface can include one or more surface modifications toallow for control over the deposition of one or more materials duringthe ECD process, as well as control over the resulting characteristicsof the electrochemically deposited nanostructures comprising at leastone LIB active material. The ECD substrate surface modification can beachieved by modification of one or more physical or chemicalcharacteristics of the substrate surface, e.g., the physical structureor chemical composition of the substrate surface. The physical orchemical characteristics of the substrate surface can be modified by oneor more mechanical, chemical, electrical, or temperature-based surfacemodification techniques, as well as additional surface modificationtechniques available in the art. Modification of the substrate surfacecan be achieved by etching (e.g., chemical, mechanical, laser, ormicro-etching), scratching, grinding, roughening, laser ablation, heattreatment, annealing, chemical treatment (e.g., acid treatment, gastreatment, foaming gas treatment, alloying, or doping) deposition of oneor more materials on the substrate surface (e.g., by coating, chemicalbinding, adsorption, binder material adhesion, lithography, sputtering,ECD or CVD, evaporation, or electroless deposition), or othermodification techniques available in the art, as well as combinationsthereof. In preferred embodiments, the substrate surface is modified tocreate discrete spatial regions on the substrate surface which have oneor more distinguishing characteristics compared to other regions of thesubstrate. Preferably, the discrete regions cause a difference insurface charge at the regions compared to other regions of thesubstrate, e.g., an opposite charge, increased charge, or decreasedcharge.

In one general class of embodiments, one or more discrete surfacefeatures, e.g., protrusions, can be formed on the substrate surface toallow for a rough substrate surface having increased activation energyat the discrete protrusions or other discrete surface features. In oneaspect of the present invention, the protrusions at the substratesurface increase the flow of electrons through the substrate at thelocation of the protrusions compared to nearby locations on thesubstrate surface. In preferred embodiments, the counter electrodeincludes a uniform or substantially uniform structure, whereby theprotrusions or other surface features have a decreased distance to thecounter-electrode compared to nearby locations on the substrate which donot include a surface protrusion. Thus, the substrate surface featuresor protrusions can provide discrete, localized active sites for directECD of discrete active material nanostructures on the substrate. Addlanguage to account for the mechanisms at work here. As will beunderstood by persons of ordinary skill in the art, the size, shape,morphology, pattern, and other characteristics of the discrete substratesurface regions and surface features can be adjusted to control thesize, shape, morphology, and other characteristics of the nanostructuresformed on the substrate surface. In preferred embodiments, the discretesurface regions have a height and/or width of 1 μm or less; morepreferably 500 nm or less, 400 nm or less, or 300 nm or less; morepreferably 250 nm or less, 200 nm or less, or 150 nm or less; mostpreferably 100 or less, 75 nm or less, 50 nm or less, 25 nm or less, 20nm or less, 15 nm or less, or 10 nm or less. Preferably, the discretesurface regions having modified surface characteristics are separatedfrom one another by a distance of at least 10 nm and less than 1 μm,e.g., the surface regions can be 10-750 nm apart, 10-500 nm apart,10-250 nm apart, 10-100 nm apart, 10-75 nm apart, 10-50 nm apart, 10-20nm apart, 20-750 nm apart, 20-500 nm apart, 20-250 nm apart, 20-100 nmapart, 20-75 nm apart, 20-50 nm apart, 50-750 nm apart, 50-500 nm apart,50-250 nm apart, 50-200 nm apart, 50-150 nm apart, 50-100 nm apart,75-250 nm apart, 75-200 nm apart, 75-150 nm apart, 75-100 nm apart,100-500 nm apart, 100-250 nm apart, 100-200 nm apart, 150-250 nm apart,150-200 nm apart, more preferably about 100 nm apart, about 75 nm apart,about 50 nm apart, about 25 nm apart, or about 20 nm apart. Mostpreferably, the distance between the center points of each surfaceregion is about two times the width of the discrete surface regions.

As shown in the example embodiments of FIGS. 39A-39F, showing top viewsof example substrate surfaces, and FIGS. 40A-E, showing cross-sectionalviews of various example substrate surfaces, the ECD substrate surfacecan include one or more first regions 3955 comprising at least onesurface modification, e.g., protrusions or other surface features ormodifications, and one or more second regions 3956, wherein the one ormore second regions 3956 do not include the surface features or includethe surface features to a lesser extent than the one or more firstregions 3955. Substrate surfaces having more than two classes of surfacemodification regions are also included in the present invention. Asshown in FIGS. 39A, 39B, 39E, and 40A-40C, the first regions 3955 andsecond regions 3956 are formed by one or more notches or trenches. Thenotches or trenches can have any shape or pattern, including arectangular shape as shown in FIGS. 39A, 39B, and 40A, or a prism,angled, or v-shape as shown in FIGS. 39E, 40B, and 40C. As shown in FIG.39F, the protrusions 3960 are high points on the substrate surfaceformed by v-shaped trenches comprising peaks 3958 and valleys 3959. Thesurface features or protrusions can have any suitable shape, includingdomes, humps, rounded features, spikes, wires, pyramids, cones, v-shapedfeatures, or square- or rectangular-shaped features, as well ascombinations thereof. As shown in the example embodiments of FIGS. 39Dand 39E, the first and second surface regions can be formed by ascratching, etching, or roughening substrate surface. As shown in theexample embodiments of FIGS. 39C, 39E, 40D, and 40F, the first andsecond regions can have a random pattern on the substrate surface. Asshown in the example embodiments of FIGS. 39A, 39C, 39D, 39F, 40A-C,40F, and 40G, the first and second regions can have an orderly orrepeating pattern on the substrate surface. In certain embodiments,e.g., as shown in FIGS. 40E and 40G, the first and regions can bedefined by a difference in the chemical composition or other surfacematerial properties. For example, the discrete surface features 4060 canbe formed by doping, heat treating, chemical treating, or otherwisemodifying the substrate material in discrete locations on the substratesurface. As will be understood by persons of ordinary skill in the art,the size, shape, morphology, pattern, and other characteristics of thediscrete substrate surface protrusions can be adjusted to control thesize, shape, morphology, and other characteristics of the nanostructuresformed on the substrate surface.

In one example embodiment, one or more active materials, one or moreinactive materials, and/or one or more conductive materials can beformed or deposited on the substrate via any suitable methods availablein the art, e.g., by coating, chemical binding, adsorption, adhesion,binder material adhesion, lithography, sputtering, ECD, CVD,evaporation, electroless deposition, or other material depositiontechniques available in the art or mentioned herein, or a combinationsthereof.

The nanostructures comprising at least one active material are directlydeposited via ECD onto at least one surface of the ECD substrate surface4116. In certain embodiments, as shown in the example embodiment of FIG.41A, the ECD substrate surface can comprise a smooth surface, wherebythe nanostructures 4120 (e.g., nanowires, tapered nanowires, dome-shapedor hump-shaped nanostructures, nanospikes, or clusters of nanospikes)are formed on the smooth substrate surface 4116. In preferredembodiments, the ECD substrate surface is a rough surface rather than asmooth surface. In preferred embodiments, the one or more ECD substratestructures comprises at least one surface having one or more surfacefeatures or protrusions. As shown in the example embodiment of FIG. 41B,the substrate comprises one or more surface features or protrusions4160, and the nanostructures 4120 are formed directly on the surfacefeatures 4160. Preferably, at least a portion of the nanostructures areformed on protrusions or surface features. More than one nanostructurecan be formed on each surface feature or protrusion. The surfaceprotrusions 4160 can comprise the same material or structure as thesubstrate. Additionally or alternatively, the substrate can comprise afirst material, and the surface protrusions 4160 can comprise a secondmaterial which is different from the first material. In another exampleembodiment, shown in FIG. 41C, the substrate includes first surfacefeatures or protrusions 4160 a comprising the substrate material andsecond surface features or protrusions 4160 b comprising a secondmaterial which is different than the substrate material. At least aportion of the second surface features or protrusions 4160 are formeddirectly over the first protrusions 4160 a, thereby forming surfaceprotrusion 4160 having an increased size or height compared to eitherthe first or second features alone. The nanostructures 4120 are formeddirectly on or over at least a portion of the stacked first and secondsurface protrusions 4160 b.

As shown in the example embodiments of FIGS. 41E-41F, the surfacefeatures can comprise at least a second material which is different thana first substrate material. These embodiments are preferred where theunderlying substrate surface is relatively smooth. The surface featuresor protrusions comprising the second material can provide increasedroughness of the substrate surface, increased conductivity at thesurface feature locations, or other characteristics which will beappreciated by persons of ordinary skill in the art. As shown in FIG.41D, the surface features include particles 4162 formed on theunderlying substrate surface 4116, whereby one or more nanostructures4120 are formed on the surface feature particles 4162. In oneembodiment, the surface features comprise graphite particles are formedon the substrate surface 4116. The particles can include othermaterials, e.g., conductive materials, copper particles, or carbonparticles. As shown in FIG. 41E, the surface features include one ormore dome-shaped or hump-shaped features 4060, whereby one or morenanostructures 4120 are formed on the surface humps or domes 4160.Additional surface feature shapes are included in the invention, e.g.,spikes, rounded features, wire-like features, spheres, or other featureshapes. In one embodiment, the surface features comprise copper formedon the substrate surface 4116. In one example embodiment, Cu iselectrochemically deposited onto the underlying substrate surface toform the features 4160. Additional material deposition or formationtechniques can be used, including techniques described herein. Thefeatures 4160 can include other materials, e.g., one or more conductivematerials, one or more metals, metal alloys, conductive polymers, one ormore binder materials, or other materials. In yet another exampleembodiment, as depicted in FIG. 41F, the surface features or protrusionsinclude one or more particles 4162 comprising a first material depositedon the substrate surface 4116 and one or more protrusions 4160 includinga second material formed on the particles 4162. The one or morenanostructures 4120 are formed on the second material. In one exampleembodiment, graphite particles are deposited on the substrate surface4116, and protrusions comprising a conductive material, e.g., Cu, areformed on the graphite particles. In another embodiment (not shown), theparticles can be formed on the protrusions formed on the substratesurface. As shown in the example embodiments of FIGS. 41G-41I, multiplenanostructures 4120 can be formed on each surface feature 4160. As shownin FIG. 411, multiple protrusions 4160 can be formed on each particle4162 which is deposited on the substrate surface 4116, and multiplenanostructures 4120 can be formed on the multiple protrusions 4160. Inanother embodiment (not shown), multiple particles can be formed on eachprotrusion formed on the substrate surface.

In another general class of embodiments, as shown in FIGS. 42A-42C, thesubstrate surface features can include trenches or indentations 4264having one or more nanostructures 4220 formed therein. The distinctregions of the substrate surface are defined by the indentations 4264which can include a variety of shapes, as shown in FIGS. 42A-42C. Thenanostructures 4220 comprising at least one active material are formeddirectly in or over the trenches/indentations 4264.

In another general class of embodiments, the substrate includes multiplelayers, wherein one or more of the substrate layers comprises discretesurface features, e.g., protrusions, as shown in FIGS. 43A-G. As shownin the figures, each LIB composite anode structure includes a firstsubstrate layer 4366, at least a second substrate layer 4368, surfaceprotrusions 4160 on the first layer 4366 and/or the second layer 4368,and at least one active material nanostructure 4320 formed over theprotrusions 4160. Two or more of the substrate layers can comprisedifferent materials or include other distinguishing characteristics. Incertain embodiments, as shown in FIGS. 43A, 43C, and 43D, theprotrusions or other surface features are formed by the surface layeritself—i.e., the substrate layer and the protrusions are integralfeatures of the same material structure or layer. In other embodiments,as shown in FIGS. 43B, 43E, and 43F, the protrusions or other surfacefeatures are formed on one or more of the layers by depositing orphysically associating one or more structures with the substrate layerto form the protrusions, wherein the structures are distinct from thesubstrate layer. Preferably, the structures comprise a material which isdifferent than the substrate material of the substrate on which thestructures are formed. As shown in FIGS. 43A-43G, the substrate cancomprise a first layer 4366 comprising a first material and at least asecond layer 4368 comprising a second material formed over the firstlayer 4366 on the top surface of the first layer 4366. The first andsecond materials can be the same material or different materials.Preferably, the first and second materials comprise different materials,different morphologies, or at least one distinguishing characteristic.

As shown in FIG. 43A, the top surface 4366 a of the first layer 4366 issubstantially smooth or flat, the second layer 4368 comprisesprotrusions 4360 on the top surface 4368 a of the second layer 4368,wherein the protrusions 4160 are an integral part of the second layer4368, and the active material nanostructures 4320 are formed on theprotrusions 4360 by direct ECD, whereby the nanostructures 4320 are indirect physical contact with the protrusions 4360 and extend outwardfrom the second layer 4368 and the protrusions 4360. As shown in FIG.43B, the top surface 4366 a of the first layer 4366 and the top surface4368 a of the second layer 4368 are substantially smooth or flat, thesecond layer 4368 comprises protrusions 4360 formed on the top surface4366 a of the second layer 4368, and the active material nanostructures4320 are formed on the protrusions 4360 by direct ECD, whereby thenanostructures 4320 are in direct physical contact with the protrusions4360 and extend outward from the protrusions 4360 and the second layer4368. As shown in FIG. 43C, the top surface 4366 a of the first layer4366 comprises protrusions 4360 which are an integral part of the firstlayer 4366, the top surface 4368 a of the second layer 4368 issubstantially smooth or flat, and the active material nanostructures4320 are formed via direct ECD on the top surface 4368 a of the secondlayer 4368 directly above the protrusions 4360, whereby thenanostructures 4320 are in physically separated from the protrusions4360 by the second substrate 4368, and the nanostructures 4320 extendoutward from the top surface 4368 a of the second substrate layer 4368.In the embodiment shown in FIG. 43D, the LIB anode structure issubstantially the same as the embodiment shown in FIG. 43C, except thatthe second substrate 4368 conforms to the shape of the first substrate4366 including the protrusions 4360 a, whereby the second substrate 4368consequently comprises protrusions 4360 b which are an integral part ofthe second substrate 4368, and the nanostructures are formed over thefirst protrusions 4360 a and the second protrusions 4360 b. In theembodiment shown in FIG. 43E, the LIB anode structure is substantiallythe same as the embodiment shown in FIG. 43C, except that theprotrusions 4360 are distinct structures from the first substrate 4366rather than being formed from the first substrate structure itself. Inthe embodiment shown in FIG. 43F, the LIB anode structure issubstantially the same as the embodiment shown in FIG. 43F, except thatthe protrusions 4360 are distinct structures from the first substrate215 rather than being formed from the first substrate structure itself.

In preferred embodiments, the one or more surface features comprise atleast one conductive material and/or at least one active material. Forexample, the surface features can include a current collector materialsuch as Cu and/or an active material such as graphite. As will beunderstood by persons of ordinary skill in the art, the size, shape,morphology, materials, pattern, and other characteristics of the surfacefeatures can be adjusted to control the size, shape, morphology, andother characteristics of the nanostructures formed thereon. The surfacefeatures or protrusions can have any suitable shape, including domes,humps, rounded features, spikes, wires, pyramids, cones, angledfeatures, v-shaped features, or square- or rectangular-shaped features,as well as combinations thereof. In preferred embodiments, the discretesurface protrusions have a height and/or width of 1 μm or less; morepreferably 500 nm or less, 400 nm or less, or 300 nm or less; morepreferably 250 nm or less, 200 nm or less, or 150 nm or less; mostpreferably 100 or less, 75 nm or less, 50 nm or less, 25 nm or less, 20nm or less, 15 nm or less, or 10 nm or less. Preferably, the discretesurface protrusions having modified surface characteristics areseparated from one another by a distance of at least 10 nm and less than1 μm, e.g., the surface regions can be 10-750 nm apart, 10-500 nm apart,10-250 nm apart, 10-100 nm apart, 10-75 nm apart, 10-50 nm apart, 10-20nm apart, 20-750 nm apart, 20-500 nm apart, 20-250 nm apart, 20-100 nmapart, 20-75 nm apart, 20-50 nm apart, 50-750 nm apart, 50-500 nm apart,50-250 nm apart, 50-200 nm apart, 50-150 nm apart, 50-100 nm apart,75-250 nm apart, 75-200 nm apart, 75-150 nm apart, 75-100 nm apart,100-500 nm apart, 100-250 nm apart, 100-200 nm apart, 150-250 nm apart,150-200 nm apart, more preferably about 100 nm apart, about 75 nm apart,about 50 nm apart, about 25 nm apart, or about 20 nm apart. Mostpreferably, the distance between the peaks or high points of eachprotrusion is about two times the width of the discrete surfaceprotrusions.

Alternatively, or in addition to the substrate surface modificationsdescribed above, one or more characteristics of the ECD substratesurface can be controlled or modified using one or more ECD processparameters or techniques of the present invention. For example, ECDprocess parameters such as the current, temperature, fluid motion,precursor concentration, or solution interaction with the substratesurface could be adjusted to have different values at the differentregions of the substrate surface. These process conditions are explainedin further detail below.

In preferred embodiments, the nanostructures comprising at least one LIBactive material and the one or more substrate materials are formed intoa LIB anode structure comprising the substrate-nanostructure composite.Using techniques available to those of ordinary skill in the art,including those mentioned herein or incorporated by reference herein,the substrate and the active material nanostructures formed thereon canbe formed into a LIB anode, and the LIB anode can be formed into a LIBfull cell or half cell for use as a rechargeable or single-use energysource.

In preferred embodiments, the anode composite structure includes aporous composite comprising one or more substrate materials and aplurality of nanostructures formed therein using one or more of the ECDmethods described herein. Preferably, the substrate-active materialnanostructure composite is a porous structure having a porosity of about10-70%, 10-50%, 20-40%, or about 30%. Preferably, the anode currentcollector and active material composite is a planar structure.Preferably, the current collector and active material composite has athickness of about 100 μm or less, preferably 100 μm or less, and mostpreferably less than 100 μm. In certain embodiments, the composite anodestructure can have one or more properties which vary over differentspatial regions of the composite. For example, the porosity,composition, or one or more other characteristics can very overdifferent spatial regions of the composite anode structure.

Binders, Electrolytes, Electrolyte Additives, and Solid ElectrolyteInterfaces

Due to the inherent differences between the material characteristics ofstandard

LIB active materials and high capacity materials and nanostructures suchas Si nanostructures, traditional LIB materials are not ideal for usewith LIBs incorporating unconventional, high-capacity active materialssuch as Si. The present invention includes novel LIB materials includingbinder materials, electrolyte materials, electrolyte additive materials,and solid electrolyte interface (SEI) materials or layers formed on oneor more battery components, as well as components, devices, and methodsof manufacturing related thereto.

Binders

One aspect of the present invention relates to LIB materials includingbinders, as well as components, devices, and methods of manufacturingrelated thereto. Particularly, the present invention includes LIBelectrolytes and LIB electrolyte additives suitable for use with LIBscomprising Si active materials or Si and graphite active materials, aswell as related components, devices, and methods. In preferredembodiments, the present invention includes a LIB anode comprising oneor more binder materials selected from the group consisting ofcarboxylmethyl cellulose (CMC), polyvinylidene fluoride (PVDF),poly(acrylamide-co-diallyldimethylammonium) (PAADAA), and polyacrylicacid (PAA), and styrene butadiene rubber (SBR).

In preferred embodiments, a LIB anode comprises Si nanostructures (e.g.,Si nanowires) and at least one binder material comprising CMC, PVDF,PAADAA, PAA, SBR, or a combination thereof. In another preferred classof embodiments, a LIB anode comprises one or more graphite structures(e.g., graphite foil or graphite particles), a plurality of Sinanostructures formed on the one or more graphite structures (e.g., Sinanowires formed on graphite particles), and at least one bindermaterial comprising CMC, PVDF, PAADAA, PAA, SBR, or a combinationthereof.

In preferred embodiments, the binder is combined with a plurality ofgraphite particles to form a slurry, then the slurry is coated onto asubstrate structure (e.g., graphite foil, carbon film, or porous carbonmesh), e.g., using traditional battery slurry coating methods. Afterevaporation of the slurry solvent, a plurality of discrete Sinanostructures are formed on the graphite particles using one or moreECD methods of the present invention.

In certain embodiments, a layer of one or more binder materials (e.g.,CMC, PVDF, PAADAA, PAA, SBR, or a combination thereof) is added directlyon a current collector substrate, and a binder-graphite particlecomposite or a binder-graphite particle-Si nanostructure composite iscoated on the current collector substrate. For example, the compositecan be coated on a Cu film or graphite foil current collector substrate.

In another class of embodiments, Si nanostructures are first formed on asubstrate comprising a plurality of graphite particles, then theSi-graphite particle composite is combined with one or more bindermaterials including CMC, PVDF, PAADAA, PAA, SBR, or a combinationthereof, to form a LIB anode. The graphite-Si-binder composite can beformed into a LIB anode, e.g., using traditional battery slurry coatingtechniques. In certain embodiments, the graphite-Si-binder composite iscoated in a LIB current collector substrate (e.g., a Cu film or graphitefoil structure) to form a LIB anode component.

The LIB anodes and LIBs of the present invention preferably include oneor more binder materials including one or more of CMC, PVDF, PAA, SBR,and PAADAA. In preferred embodiments, the binder includes CMC, PAADAA,SBR, and/or PAA. For example, the LIB anode structure can include aplurality of graphite particles having Si nanostructures formed thereon,wherein the graphite particles are bound together using a CMC, PAADAA,SBR, and/or PAA binder material. Additionally, the graphite-Si-CMCbinder composite can be formed on a current collector substrate (e.g., aplanar Cu substrate) using one or more binder materials such as PAA. Inone embodiment, the graphite-Si composite material is formed on acurrent collector, wherein one or more of a CMC, PVDF, PAA, and PAADAAbinder material is disposed between the current collector structure andthe graphite-Si active material composite, thereby improving the bondstrength between the current collector and the graphite-Si compositematerial.

In preferred embodiments, PAA is disposed between a LIB currentcollector structure and the graphite powder-Si composite material, andthe same binder material or one or more different binder materials isused to bind the graphite powder particles together. For example, CMCand/or PAADAA can be used to bind the graphite particles together in theSi-graphite powder composite structure, and PAA can be used as aninterface binder material between the graphite powder-Si composite andthe current collector.

In certain embodiments, the binder composition, binder concentration, orconcentration of different binder materials can be varied over differentspatial regions of the LIB anode or the LIB anode active materialcomposite. For example, a first binder material (e.g., PAA) can have ahigher concentration than a second binder material (e.g., CMC) at aninterface between the LIB anode current collector structure (e.g., Cufilm) and an active material composite structure (e.g., graphitepowder-Si nanostructure composite), and the concentration of the firstbinder material can be lower at a distance away from the interface. Forexample, the first binder material can have a gradient concentrationwhich decreases in a direction away from the interface.

The ratio of binder materials to conductive and active materials in theLIB anode will vary depending on the composition of the respectivecomponents. The LIB anode active material composite can comprise abinder material, wherein the active material composite consists of lessthan 10% of the binder material, less than 5% of the binder material,less than 4% of the binder material, or about 3-4% of the bindermaterial. In preferred embodiments, the LIB anode includes less than 10%binder material. Most preferably, the binder concentration is less thanabout 5%, less than 5%, less than about 4%, less than 4%, less thanabout 3%, or less than 3%. The LIB anode can include any suitable bindermaterials, including CMC, PVDF, PAA, SBR, or PAADAA, or combinationsthereof, including CMC and PAA, CMC and PAADAA, or CMC, PAA, and PAADAA.

In certain embodiments, the LIB anode can be formed without using anybinder materials. For example, no binder material is required whenactive material nanostructures are formed directly on a LIB anodecurrent collector structure such as Cu film or graphite foil.Advantageously, these embodiments reduce the overall weight of the anodestructure and reduce the number of different materials and impurities inthe LIB anode.

Electrolytes, Electrolyte Additives, and SEIs

One aspect of the present invention relates to LIB materials includingelectrolytes and electrolyte additives, as well as components, devices,and methods of manufacturing related thereto. Particularly, the presentinvention includes LIB electrolytes and LIB electrolyte additivessuitable for use with LIBs comprising Si active materials or Si andgraphite active materials, as well as related components, devices, andmethods. In preferred embodiments, the electrolyte is a liquid polymerelectrolyte. In one embodiment, the present invention includes a LIBanode comprising one or more electrolyte materials comprising at leastone liquid polymer solvent selected from the group consisting of diethylcarbonate (DEC), ethylene carbonate (EC), or ethyl methyl carbonate(EMC); and at least one polymer additive selected from the groupconsisting of fluorinated ethylene carbonate (FEC), diallylpyrocarbonate (DAPC), diethyl pyrocarbonate (DEPC), diallyl carbonate(DAC), diallyl succinate (DAS), tris(pentafluorophenyl) bora (TPFPB),tris(2,2,2-trifluoroethyl) posphite (TTFP),N,N′-dicyclohexylcarbodiimide (DCC), methoxy trimethyl silane (MOTS),dimethoxydimethylsilane (DMOS), trimethoxy methyl silane (TMOS), maleicanhydride (MA), succinimide (SI), n-(benzyloxycaronyloxy)succinimide(NBSI), vinylene carbonate (VC), vinyl ethylene carbonate (VEC),1,3-propanesultone (PS), polydimethylsiloxane (PDMS), maleic anhydride(MA), and succinic anhydride (SA). In preferred embodiments, the LIBanode active material includes Si nanostructures or a combination of Sinanostructures and graphite (e.g., graphite foil or powder).

Advantageously, the electrolytes and electrolyte additives of thepresent invention provide an appropriate SEI on the Si and graphitestructure surfaces that can also be self-healed during battery chargeand discharge cycling. Without changing the Si structure, the SEIminimizes the side reactions between Si or graphite and the electrolytewhile allowing for sufficient diffusion of Li ions through the SEIlayer, allowing penetration of Li ions from the electrolyte solution tothe Si or Si and graphite active materials.

In one preferred class of embodiments, a LIB anode comprises Si andgraphite active materials and an electrolyte comprising EC and DEC; orEC, DEC, and EMC. Preferably, the electrolyte further comprises anadditive comprising FEC. Most preferably, the LIB comprises Si andgraphite active materials and an electrolyte comprising about 90% of asolvent mixture comprising equal parts of DEC:EC:EMC and about 10% of anadditive comprising one or more materials selected from the groupconsisting of FEC, SA, and DAPC. Most preferably, the electrolytecomprises DEC, EC, EMC, and FEC. For example, the electrolyte cancomprise an electrolyte comprising about 90% of a solvent mixturecomprising equal parts of DEC:EC:EMC and about 10% of an additivecomprising FEC, FEC and DAPC, or FEC and SA.

In preferred embodiments, the LIB comprises Si or Si and graphite activematerials and an electrolyte. Preferably, the electrolyte comprises oneor more additive materials which provides a self-healing SEI layer onthe Si or Si and graphite active materials during LIB charge anddischarge cycling. In preferred embodiments, the self-healing SEI layeris formed via reduction of one or more electrolyte additive materialsonto the active material surface during LIB charge cycling, wherein theelectrolyte additive material comprises FEC, DAPC, MA, SI, NBSI, SA, ora combination thereof. Most preferably, the electrolyte additivecomprises FEC.

In preferred embodiments, the SEI layer can be formed as an artificialSEI layer. The artificial SEI layer can be formed in an electrolyticcell prior to formation of the LIB anode. For example, the LIB anodeactive material nanostructures can be formed using one or more ECDmethods of the present invention, and the SEI layer can be formed on theactive material nanostructures in the same electrolytic cell or adifferent electrolytic cell by adding one or more SEI precursors to formthe SEI layer via ECD directly on the active material surface.

In preferred embodiments, the LIB anode active material compositecomprises about 65-95% graphite active material, about 5-45% Si activematerial, and about 3-6% binder material. In certain embodiments, nobinder material is required.

ECD Processes

As described above, the present invention includes novel, cost-effectivemethods for producing high-quality, high-capacity active materialnanostructures for use in LIB components and devices, includingsilicon-based or tin-based nanostructures for use as LIB anode activematerials. Particularly, the present invention allows forlow-temperature, catalyst-free, template-free ECD processes forproducing discrete active material nanostructures, eliminating the needfor removal of catalyst materials, template materials, or impuritiesintroduced by catalyst or template materials. The ECD processes of thepresent invention provide methods for controlling the physical andchemical characteristics of the active material nanostructures to meetspecific requirements consistently over multiple process runs, therebyproviding an effective process solution for mass-production ofhigh-quality and high-capacity LIB anode active materials. For example,the ECD methods of the present invention allow for formation of highlycrystalline active material nanostructures at low temperatures (e.g.,room temperature) immediately upon deposition onto the desired substratewithout the need for subsequent annealing to achieve crystallinity. Inpreferred methods, active material nanostructures are electrochemicallydeposited directly onto one or more substrates comprising at least oneLIB anode active material (e.g., graphite) and/or LIB anode currentcollector structure (e.g., a copper, graphite, or nickel electrode) toform a LIB anode component, thereby improving adhesion between thenanostructures and the substrate as well as eliminating the need toremove the nanostructures from the ECD growth substrate for inclusion inthe LIB anode. Using techniques available to those of ordinary skill inthe art, the substrate and the active material nanostructures formedthereon can be formed into a LIB anode, and the LIB anode can be formedinto a LIB full cell or half cell for use as a rechargeable orsingle-use energy source. Furthermore, the high quality of the LIBactive materials produced by the ECD processes of the present inventionprovide consistency and predictability of battery system performance andallow for control over changes to these materials and related batterydevices throughout the multiple charge cycles and various conditions towhich they are subjected. These high-quality materials eliminate theirreversible, undesired side effects which contribute to unpredictableand detrimental changes in LIBs and cause large hysteresis in theoperation characteristics of LIBs.

It is to be understood that any of the materials described herein can beused in the processes of the present invention, including, but notlimited to, active material nanostructures, substrate materials, currentcollector materials, current collector substrate materials, activematerials, substrates comprising active materials, binder materials,electrolytes, electrolyte component materials, electrolyte additivematerials, SEI materials, LIB anode materials, or other LIB componentmaterials described herein. For the sake of brevity, these materials maynot be independently described in connection with the description of themethods and processes of the present invention. However, it is to beunderstood that all such materials mentioned herein and their variouscombinations can be used as materials in the methods and processes ofthe present invention.

In general, preferred ECD processes of the present invention include anelectrolytic cell (EC) for ECD, wherein the EC is similar to the exampleEC shown in FIG. 44. The EC includes a container 4412, an electricallyconductive working electrode (i.e., EC cathode) 4406, anelectrochemically stable current electrode (i.e., EC anode) 4407, areference electrode 4409, a potential voltage source 4408 providingdirect current 4411 through the EC, a potentiostat 4413, and anelectroactive supporting electrolyte solution 4404 comprising one ormore precursor materials dissolved in one or more solvent materials. Theelectrochemical reaction results in the nanostructures 4420 comprisingone or more active materials are formed directly on one or more surfacesof the working electrode 4406.

The reference electrode 4409 preferably includes a platinum referenceelectrode, e.g., a Pt wire.

The current electrode 4407 can include Pt, C, Cu, graphite, anotherconductive material, or any combination of these and other conductivematerials. For example, the current electrode can include a carbonsheet, carbon foil, carbon paper, Cu foil, Cu foam, Cu sponge, graphitefoil, another conductive substrate structure, one or more of thesesubstrate structures, or any combination of these or other conductivesubstrate structures. In preferred embodiments, the current electrodecomprises carbon paper. In certain embodiments, the counterelectrode/current electrode 4408 can include a noble metal material toprovide a stable counter electrode.

In preferred embodiments, the working electrode 4406 and the currentelectrode 4408 are separated in the electrolytic cell by a distance ofabout 2 cm. As will be understood by persons of ordinary skill in theart, the voltage can be fixed during the ECD process while the currentflow can be varied as the distance between the working and counterelectrodes changes.

The working electrode 4406 can include any of the ECD substratematerials and structures mentioned herein. The working electrode caninclude one or more conductive substrate materials or a combination ofone or more conductive substrate materials and one or moresemiconductor, insulator, and/or non-substrate conductive materials. Theworking electrode can comprise one or more metals, Cu, C, graphite, Ni,steel, Al, Pt, Au, Sn, one or more conductive polymers, other conductivematerials, one or more binder materials such as CMC, PVDF, PAA, orPAADAA, as well as any composition, mixture, alloy, or combinationthereof. In certain embodiments, the working electrode comprisesmultiple materials, e.g., Cu and graphite, non-graphitic C and graphite,Ni and graphite, steel and graphite, Al and graphite, Pt and graphite,Cu and C, Cu and Sn, C and Sn, multiple forms of graphite, multipleforms of C; Cu, non-graphitic C, and graphite; graphite and one or morebinder materials, or any composition, mixture, alloy, or combinationthereof. In preferred embodiments, the working electrode includes one ormore LIB active materials or structures and/or one or more LIB currentcollector materials or structures. Exemplary working electrodestructures include one or more of the following: graphite foil or plate,polished graphite foil or plate, graphite flakes or particles, graphiteflakes or particles and one or more binder materials such as CMC, PVDF,PAA, or PAADAA, graphite flakes or particles combined with one or morebinder materials and coated on graphite foil or plate, Cu-coatedgraphite foil, Cu-coated graphite foil coated with graphite flakes orparticles, graphite flakes or particles combined with one or more bindermaterials and coated on a Cu-coated graphite foil or plate, Cu-coatedgraphite foil or plate subjected to gas treatment, porous Cu mesh orfoam, Cu wires, Cu fibers, Ni-coated Cu wires or fibers, patterned Cuwires, Ni-coated patterned Cu wires, carbon sheet, heat-treated carbonsheet, Cu foil or plate coated with graphite flakes or particles,graphite flakes or particles combined with one or more binder materialsand coated on a Cu foil or plate, graphite flakes or particles disposedbetween or pocketed by porous Cu mesh sheets, graphite flakes orparticles combined with one or more binder materials and disposedbetween or pocketed by porous Cu mesh sheets, one or more bindermaterials such as CMC, PVDF, PAA, or PAADAA, and combinations thereof.

In one class of embodiments, the working electrode 4406 comprisesCu-coated graphite foil or a Cu-coated carbon sheet. Cu iselectrochemically deposited onto a carbon sheet or graphite foilsubstrate to form a working electrode and ECD substrate comprisingCu-coated graphite foil. For example, an EC similar to the one shown inFIG. 1A can be used to coat the Cu onto the carbon sheet or graphitefoil substrate. The Cu coating can comprise a complete layer of Cu orone or more surface features comprising Cu formed on the underlyingsubstrate. At least one Cu precursor is dissolved in at least onesolvent to form the electrolyte solution for deposition of Cu onto thegraphite foil or carbon sheet substrate. For example, the solution 104can comprise a cupric sulfate (CuSO₄) precursor dissolved in an ionicliquid solvent comprising non-aqueous non-aqueous n-methyl-n-butylpyrrolidinium bis(trifluoromethanesulfonyl)imide (P1,4TFSI) or distilledionized water (DI H₂O). [Does DI H₂O mean distilled ionized water,deionized water, distilled water, or something else?] For example, thesolution can comprise less than about 0.03M CuSO₄ in P_(1,4)TFSI (e.g.,about 0.002-0.02M CuSO₄ in P_(1,4)TFSI) or less than about 0.15M CuSO₄in DI H₂O (e.g., about 0.5-0.1M CuSO₄ in DI H₂O).

The EC electrolyte solution 104 comprises at least one active materialprecursor dissolved in at least one solvent. Suitable electrolytes forECD of Si nanostructures include organic solutions; high-, middle-, andlow-temperature molten salts; or room-temperature ionic liquids.Preferred solutions have a wide electrochemical potential window,sufficient conductivity, negligible vapor pressure, and immiscibilitywith water. As will be understood by persons of ordinary skill in theart, the reduction potential of the material to be deposited ispreferably lower than the reduction potential of the solvent or othermaterials in the ionic solution in order to avoid reduction of thesolvent or other materials before reduction of the desired material tobe deposited. In preferred embodiments, the solvent includesP_(1,4)TFSI. In other embodiments, the solvent can include distilled ordeionized water (DI H₂O), acetonitrile (ACN), or propylene carbonate(PC).

In preferred embodiments, the EC solution 104 comprises a Si precursorincluding trichlorosilane (SiHCl₃) and/or silicon tetrachloride (SiCl₄).In preferred embodiments, a Si precursor (e.g., SiHCl₃ or SiCl₄) isdissolved in an ionic liquid solvent comprising P_(1,4)TFSI or DI H₂O.For example, the ECD methods of the present invention can include ECD ofSi nanostructures onto a working electrode substrate 215 comprisinggraphite and/or copper, a Si precursor (e.g., SiHCl₃ or SiCl₄) isdissolved in an electrolyte solvent (e.g., P_(1,4)TFSI), the Si andchlorine (Cl) precursor ions, or the Si, Cl, and hydrogen (H) precursoratoms, are separated by the redox reaction, and Si atoms are depositedonto the working electrode as discrete nanostructures. During this ECDprocess, discrete Si nanostructures such as Si nanowires form on the Cuand/or graphite working electrode substrate. The amount or concentrationof SiHCl₃ silicon precursor can be about 0.1M to about 1M, preferably0.5M to about 1M, about 0.5M to about 0.9M, 0.5M to 1M, or 0.5M to 0.9M.The amount or concentration of SiCl₄ silicon precursor can be about0.05M to about 0.5M, preferably 0.05M to 0.5M, about 0.05 to about0.04M, or 0.05M to 0.04M. Most preferably, the active material comprisesSi and the precursor comprises SiHCl₃; most preferably, the solution 104comprises SiHCl₃ dissolved in P_(1,4)TFSI solvent. Most preferably, thesolution 104 comprises about 0.6M SiHCl₃ dissolved in P_(1,4)TFSI.

While Si is the preferred active material for ECD, other materials canalso be used, including those mentioned herein. ECD of most metals canbe achieved using a metallic salt precursor dissolved in a suitablesolvent material. For example, discrete Sn nanostructures can be formedvia ECD using a tin chloride (SnCl₂) precursor dissolved in anappropriate solvent material.

In certain embodiments, the EC can include multiple working electrodesand/or multiple precursor materials. In one example embodiment, Si andCu are co-deposited via ECD onto a graphite foil substrate, wherein theEC solution comprises a Cu precursor and at least one Si precursordissolved in a solvent, e.g., CuSO₄ and SiHCl₃ dissolved in P_(1,4)TFSI.

Important factors for controlling the deposition and morphology duringECD of active material nanostructures include: deposition voltage,precursor composition, precursor concentration, electrolyte composition,current density, ECD process temperature, and deposition time.

As illustrated by the different Si nanostructures shown in FIGS. 6-22,the precursor material and concentration affect Si growth andmorphology.

FIGS. 6A-6B show the resulting Si nanostructures formed on a graphitefoil substrate using an EC solution comprising 1M SiHCl₃ in P_(1,4)TFSI,with an applied voltage of −2.9V vs. the Pt reference electrode. FIGS.7A-7B show the resulting Si nanostructures formed on a graphite foilsubstrate using an EC solution comprising 1M SiHCl₃ in P_(1,4)TFSI, withan applied voltage of applied voltage of −2.7V vs. the Pt referenceelectrode. FIGS. 8A-8B show the resulting Si nanostructures formed on agraphite foil substrate using an EC solution comprising 0.9M SiHCl₃ inP_(1,4)TFSI, with an applied voltage of −3V vs. the Pt referenceelectrode. FIGS. 9A-9B show the resulting Si nanostructures formed on agraphite foil substrate using an EC solution comprising 0.7M SiHCl₃ inP_(1,4)TFSI, with an applied voltage of −3V vs. the Pt referenceelectrode. FIGS. 10A-10B show the resulting Si nanostructures formed ona graphite foil substrate using an EC solution comprising 0.6M SiHCl₃ inP_(1,4)TFSI, with an applied voltage of −3V vs. the Pt referenceelectrode. FIGS. 11A-11B show the resulting Si nanostructures formed ona graphite foil substrate using an EC solution comprising 0.4M SiHCl₃ inP_(1,4)TFSI, with an applied voltage of −3V vs. the Pt referenceelectrode. FIGS. 12A-12C show the resulting Si nanostructures formed ona graphite foil substrate using an EC solution comprising 0.2M SiHCl₃ inP_(1,4)TFSI, with an applied voltage of applied voltage of −3V vs. thePt reference electrode. FIGS. 13A-13B show the resulting Sinanostructures formed on a graphite foil substrate using an EC solutioncomprising 0.2M SiHCl₃ in P_(1,4)TFSI, with an applied voltage of −2.8Vvs. the Pt reference electrode. FIGS. 14A-14C show the resulting Sinanostructures formed on a graphite foil substrate using an EC solutioncomprising 0.1M SiHCl₃ in P_(1,4)TFSI, with an applied voltage of −2.5Vvs. the Pt reference electrode. FIGS. 15A-15B show the resulting Sinanostructures formed on a graphite foil substrate using an EC solutioncomprising 0.05M SiHCl₃ in P_(1,4)TFSI, with an applied voltage of −3Vvs. the Pt reference electrode. FIGS. 16A-16B show the resulting Sinanostructures formed on a graphite foil substrate using an EC solutioncomprising 0.05M SiHCl₃ in P_(1,4)TFSI, with an applied voltage of −2.5Vvs. the Pt reference electrode.

FIGS. 17A-17B show the resulting Si nanostructures formed on a graphitefoil substrate using an EC solution comprising 0.4M SiCl₄ inP_(1,4)TFSI, with an applied voltage of −3V vs. the Pt referenceelectrode. FIGS. 18A-18B show the resulting Si nanostructures formed ona graphite foil substrate using an EC solution comprising 0.4M SiCl₄ inP_(1,4)TFSI, with an applied voltage of −3V vs. the Pt referenceelectrode. FIGS. 19A-19C show the resulting Si nanostructures formed ona graphite foil substrate using an EC solution comprising 0.1M SiCl₄ inP_(1,4)TFSI, with an applied voltage of −3V vs. the Pt referenceelectrode. FIGS. 20A-20B show the resulting Si nanostructures formed ona graphite foil substrate using an EC solution comprising 0.1M SiCl₄ inP_(1,4)TFSI, with an applied voltage of −3.2V vs. the Pt referenceelectrode. FIGS. 21A-21B show the resulting Si nanostructures formed ona graphite foil substrate using an EC solution comprising 0.05M SiCl₄ inP_(1,4)TFSI, with an applied voltage of −3.1V vs. the Pt referenceelectrode. FIGS. 22A-22B show the resulting Si nanostructures formed ona graphite foil substrate using an EC solution comprising 0.05M SiCl₄ inP_(1,4)TFSI, with an applied voltage of −3V vs. the Pt referenceelectrode. Due to the fact that the SiCl₄ precursor makes Si depositionmore difficult to control, a SiHCl₃ precursor is preferred over SiCl₄.

As will be appreciated by persons of ordinary skill in the art,variations in the precursor composition or concentration may result inchanges to the pH of the solution and/or the miscibility of theprecursor with the solvent, thereby affecting the mobility of the ionsof the material to be deposited, and thus changing the characteristicsof the electrochemically deposited material. As explained above, theprecursor composition or concentration can be varied to control thesize, shape, morphology, or other characteristics of theelectrochemically deposited nanostructures.

In preferred embodiments, a constant potential voltage is applied to theEC during the ECD process. The constant potential voltage applied can beabout −2V to about −3V vs. a Pt reference electrode. Preferably, aconstant potential voltage is applied at about −2.4V to about −2.8Vcompared to a Pt reference electrode. These voltage and current rangeshave been optimized for the specific process embodiments mentionedherein. In preferred embodiments, a constant direct current of about 1mA/cm² to about 8 mA/cm² is applied to the EC during the ECD process.Preferably, a constant direct current is applied at about 0.5 mA/cm² toabout 1.5 mA/cm². In preferred embodiments, the reaction is stopped whenthe measured current falls below about 100 mA. In certain embodiments,the structure and size of the Si deposit can be adjusted by changing thedeposition potential/current. However, as will be understood by personsof ordinary skill in the art, the applied voltage and current can bevaried with the selection of substrate materials, precursors,electrolytic cell electrolytes, etc. Such variations are included in thepresent invention.

The voltage and current profiles are important for controlling Simorphology during the ECD project. In preferred embodiments, the ECDprocess includes applying a constant potential of about −2.5V to about−3V for about three hours at room temperature. In one exampleembodiment, the applied potential for ECD of Si can be determined fromthe reduction peak of Si attained using linear sweep voltammetry atsweep rate of 5 mV/s. FIG. 45A shows the current and voltage profile for0.5M SiHCl₃ dissolved in a PC solvent at a sweep rate of 5 mV/s, andFIG. 45B shows the current and voltage profile for 0.5M SiCl₄ dissolvedin a P_(1,4)TFSI solvent with a constant applied voltage of 5 mV/s. TheSi reduction potential can be determined from the graphs of FIGS. 45Aand 45B. FIG. 46 shows the current profiles for ECD of 0.1M SiHCl₃ 4672dissolved in a P_(1,4)TFSI solvent with a constant potential of −2.5Vand 0.1M SiCl₄ 4674 dissolved in a P_(1,4)TFSI solvent with a constantpotential of −3V.

The ECD methods of the present invention can be performed at lowtemperatures such as room temperature. In preferred embodiments, the ECDof nanostructures comprising at least one active material is performedat about 80° C. or less, about 70° C. or less, about 60° C. or less,about 50° C. or less, about room temperature, or room temperature.

In certain embodiments, the ECD process includes controlling one or moreof the potential voltage, the current, and the concentration of theprecursor and electrolyte, and the temperature to control the sizeand/or structure of the electrochemically deposited active materials.

As will be understood by persons of ordinary skill in the art, thestructure and size of the active material nanostructures can be adjustedby changing the operating temperature of the ECD process. In preferredembodiments, the ECD process is performed at room temperature. Inpreferred embodiments, the ECD process is performed at atmosphericpressure and ambient temperature.

In preferred embodiments, the reaction is stopped when the measuredcurrent falls below about 100 mA. The ECD reaction time can be performedover a period of about 1-3 hours, most preferably about 2-3 hours.

In preferred embodiments, the EC solution 4704 is subjected to one ormore forces resulting in fluid motion during the ECD process. Forexample, as shown in FIG. 47, the EC solution 4704 can be stirred, e.g.,using a magnetic stir plate 4776 and a magnet 4778 inside theelectrolytic cell. In certain embodiments, the fluid motion 4780 of thesolution 4704 in the EC provides uniform dispersion of the Si precursorin the solution.

In other embodiments, the fluid motion is varied in different regions ofthe working electrode, resulting in varied Si concentration or varied Sideposition on the working electrode substrate. For example, differentflow rates can be applied to the solution at different regions of thesubstrate. In still other embodiments, the fluid flow can be pulsed toprovide time-dependent changes in the fluid flow rate in theelectrolytic solution. In another class of embodiments (not shown in thefigures), the electrolytic cell can include a flow channel so that fluidenters the EC container at one location and exits the container adifferent location, whereby the fluid flows past the working electrodesubstrate.

In one class of embodiments, as shown in FIG. 48, the electrolytic cellcomprises a first region 4882 and a second region 4884, wherein thefirst and second regions are separated by a porous separator 4883. Theprecursor solution 4804 flows freely through the separator 4883 to allowfor deposition of one or more active materials on the particulatesubstrate 4815 (e.g., graphite powder). The separator 4883 can includean insulator material such as a porous ceramic or polymeric insulator,or the separator 4883 can include a metallic material such as a porousCu separator.

In another class of embodiments, as shown in FIG. 49, a particulatesubstrate 4915 is disposed within a porous working electrode 4906. Forexample, a substrate material comprising graphite powder can be disposedwithin a pocket 4906 b of the porous Cu mesh working electrode 4906. Thesolvated active material ions (e.g, Si ions) can flow freely through theporous working electrode 4906. For example, this embodiment can be usedto form the anode structures described above in FIGS. 26A-27B and30A-31D.

In another general class of embodiments, the ECD of one or more activematerial nanostructures on a current collector or active materialsubstrate can be controlled by adjusting the temperature or electricalcurrent of the solution, the substrate, and/or the working electrodeover different regions of the ECD substrate.

In another general class of embodiments, the active materialnanostructures are subjected to one or more pre-lithiation orpre-lithiation and delithiation procedures prior to forming the LIBanode. Preferably, such pre-lithiation or pre-lithiation anddelithiation can be performed in an electrolytic cell, including thesame EC used to deposit the active material nanostructures using ECD ora different EC from the active material deposition EC. In preferredembodiments, the ECD process further comprises lithiating theelectrochemically deposited nanostructures after the ECD process. In oneexample embodiment, this process includes providing a solutioncomprising a lithium precursor dissolved in at least one solvent in theelectrolytic cell and applying a potential voltage to the electrolyticcell to reduce the lithium, wherein lithium atoms alloy with the activematerial nanostructures (e.g., Si nanostructures), resulting inlithiation of the nanostructures. Subsequently, the nanostructures andthe substrate materials can be formed into a LIB anode comprisingpre-lithiated (or pre-lithiated and delithiated) active materialnanostructures. The lithium precursor solution can comprise at least onelithium salt precursor material including lithium hexafluorophosphate(LiPF₆) and/or lithium bis(oxatlato)borate (LiBOB).

Exemplary embodiments of the present invention have been presented. Theinvention is not limited to these examples. These examples are presentedherein for purposes of illustration, and not limitation. Alternatives(including equivalents, extensions, variations, deviations, etc., ofthose described herein) will be apparent to persons skilled in therelevant art(s) based on the teachings contained herein. Suchalternatives fall within the scope and spirit of the invention. Whilethe foregoing invention has been described in some detail for purposesof clarity and understanding, it will be clear to one skilled in the artfrom a reading of this disclosure that various changes in form anddetail can be made without departing from the true scope of theinvention. For example, all the techniques and apparatus described abovecan be used in various combinations. All publications, patents, patentapplications, and/or other documents cited in this application areincorporated by reference in their entirety for all purposes to the sameextent as if each individual publication, patent, patent application,and/or other document were individually indicated to be incorporated byreference for all purposes.

1. A method of forming a lithium-ion battery (LIB) component,comprising: providing at least one substrate structure; andelectrochemically depositing a plurality of nanostructures directly ontoone or more surfaces of the at least one substrate structure, whereinthe nanostructures are formed via electrochemical deposition without agrowth template.
 2. The method of claim 1, wherein the LIB component isa LIB anode component.
 3. The method of claim 1, wherein the pluralityof nanostructures comprise at least one LIB anode active material. 4.The method of claim 3, wherein the nanostructures comprise silicon (Si),one or more intermetallic compounds and/or alloys of Si, tin (Sn), oneor more intermetallic compounds and/or alloys of Sn, or Si and Sn,wherein the one or more intermetallic compounds of Si are asilicon-copper (Si—Cu) intermetallic compound, a silicon-nickel (Si—Ni)intermetallic compound, or any combination thereof; and wherein the oneor more intermetallic compounds of Sn are a tin-copper (Sn—Cu)intermetallic compound, a tin-nickel (Sn—Ni) intermetallic compound, atin-manganese (Sn—Mn) intermetallic compound intermetallic compound, orany combination thereof. 5-10. (canceled)
 11. The method of claim 1,wherein the substrate structure comprises at least one current collectorstructure.
 12. The method of claim 7, wherein the at least one currentcollector substrate structure comprises at least one copper (Cu)structure and/or at least one graphite structure.
 13. The method ofclaim 8, wherein the at least one current collector substrate structurecomprises one or more of a Cu film, Cu foil, a Cu mesh structure, and aCu sponge structure.
 14. The method of claim 8, wherein the at least onecurrent collector substrate structure comprises one or more of agraphite film, carbon paper, a graphite foil structure, graphite powder,and carbon powder.
 15. The method of claim 1, wherein the substratestructure comprises at least one active material structure.
 16. Themethod of claim 15, wherein the at least one active material substratestructure comprises graphite, wherein the at least one active substratestructure comprises graphite, wherein the graphite active materialsubstrate structure comprises graphite powder having a plurality ofgraphite flakes or particles, and wherein the graphite powder iscombined with one or more binder materials to adhere the graphiteparticles or flakes together. 17-18. (canceled)
 19. The method of claim18, wherein the one or more binder materials include one or more ofcarboxylmethyl cellulose (CMC), polyvinylidene fluoride (PVDF), styrenebutadiene rubber (SBR), or polyacrylic acid (PAA). 20-21. (canceled) 22.The method of claim 18, wherein the combining is performed prior toelectrochemically depositing the plurality of nanostructures on one ormore surfaces of the graphite powder.
 23. The method of claim 18,wherein the plurality of nanostructures are electrochemically depositedon one or more surfaces of the graphite powder prior to combining thegraphite powder with one or more binder materials to adhere the graphiteparticles or flakes together.
 24. The method of claim 1, wherein theproviding at least one substrate structure comprises coating graphitepowder onto a graphite foil structure or a porous Cu structure.
 25. Themethod of claim 24, wherein the coating comprises coating a graphitepowder and one or more binder materials onto the graphite foil or porousCu structure.
 26. The method of claim 1, wherein the providing at leastone substrate structure comprises disposing graphite powder comprising aplurality of graphite particles or graphite flakes between two or moreporous Cu structures.
 27. The method of claim 26, wherein the providingfurther comprises combining the graphite powder with at least one bindermaterial prior to disposing the graphite powder between the two or moreporous Cu structures.
 28. The method of claim 1, wherein the pluralityof nanostructures are electrochemically deposited directly onto the oneor more surfaces of the at least one substrate structure, wherein thenanostructures are in direct physical contact with the one or moresurfaces of the at least one substrate structure.
 29. The method ofclaim 1, wherein the nanostructures are formed as highly crystallinenanostructures comprising at least one active material.
 30. The methodof claim 29, wherein the nanostructures are formed as highly crystallinenanostructures immediately upon formation, whereby no further processingis required to achieve the crystalline structure of the nanostructure.31. The method of claim 29, wherein the nanostructures comprisemonocrystalline Si.
 32. The method of claim 1, wherein thenanostructures comprise highly crystalline Si, wherein the nanostructureare substantially free of amorphous Si or polycrystalline Si uponformation.
 33. The method of claim 1, wherein the nanostructurescomprise elongated nanostructures, Si nanowires, Si nanospikes, clustersof Si nanospikes, or clusters of Si nanowires, wherein the elongatednanostructures comprises nanowires, tapered nanowires, nanospikes,clusters of nanospikes, or clusters of nanowires. 34-35. (canceled) 36.The method of claim 1, wherein at least one substrate structurecomprises at least one substrate structure comprising plurality ofsurface features formed on at least one surface of the substratestructure, wherein the depositing comprises forming the one or morenanostructures directly on the one or more surface features.
 37. Themethod of claim 36, wherein the surface features comprise a plurality ofprotrusions formed on at least one surface of the one or more substratestructures.
 38. The method of claim 36, wherein the surface featurescomprise a plurality of indentations or trenches formed on at least onesurface of the one or more substrate structures.
 39. The method of claim1, wherein the electrochemical deposition is performed at about 80° C.or less, about 70° C. or less, about 60° C. or less, about 50° C. orless, about room temperature, or room temperature.
 40. The method ofclaim 1, further comprising forming a LIB anode component comprising theat least one substrate structure and the plurality of nanostructuresformed thereon.
 41. The method of claim 40, wherein the at least onesubstrate structure comprises graphite powder and the nanostructurescomprise Si nanostructures electrochemically deposited on the graphitepowder, wherein the LIB anode composite comprises a porous activematerial composite including the graphite powder and Si nano structures.42. The method of claim 41, wherein the active material composite has aporosity of about 1-50%.
 43. The method of claim 42, wherein the activematerial composite comprises a binder material, wherein the activematerial composite consists of less than 10% of the binder material,less than 5% of the binder material, less than 4% of the bindermaterial, or about 3-4% of the binder material.
 44. The method of claim43, wherein the binder material comprises CMC.
 45. A method of forming alithium-ion battery (LIB) component, comprising: providing at least onesubstrate structure; and electrochemically depositing a plurality ofnanostructures directly onto one or more surfaces of the at least onesubstrate structure, wherein the nano structures are nanocrystalscomprising at least one active material, wherein the nanocrystals areformed as highly crystalline nanocrystals immediately upon formation viaelectrochemical deposition such that no further processing is requiredafter electrochemical deposition to achieve the crystalline structure ofthe nanocrystals. 46-86. (canceled)
 87. A method of forming alithium-ion battery (LIB) component, comprising: providing at least onesubstrate structure comprising graphite; and electrochemicallydepositing a plurality of nanostructures directly onto one or moresurfaces of the at least one graphite substrate structure. 88-127.(canceled)
 128. A method of forming a lithium-ion battery (LIB)component, comprising: providing an electrolytic cell comprising aworking electrode, wherein the working electrode comprises at least onesubstrate structure comprising one or more LIB current collectorstructures and/or one or more LIB active material structures; andelectrochemically depositing a plurality of Si nanostructures directlyonto one or more surfaces of the at least one substrate structure.129-135. (canceled)
 136. A LIB comprising: an anode comprising at leastone active material, wherein the at least one active material includesSi and graphite; and an electrolyte comprising: at least one liquidpolymer solvent selected from the group consisting of diethyl carbonate(DEC), ethylene carbonate (EC), or ethyl methyl carbonate (EMC); and atleast one polymer additive selected from the group consisting offluorinated ethylene carbonate (FEC), diallyl pyrocarbonate (DAPC),diethyl pyrocarbonate (DEPC), diallyl carbonate (DAC), diallyl succinate(DAS), tris(pentafluorophenyl) bora (TPFPB), tris(2,2,2-trifluoroethyl)posphite (TTFP), N,N′-dicyclohexylcarbodiimide (DCC), methoxy trimethylsilane (MOTS), dimethoxydimethylsilane (DMOS), trimethoxy methyl silane(TMOS), maleic anhydride (MA), succinimide (SI),n-(benzyloxycaronyloxy)succinimide (NBSI), vinylene carbonate (VC),vinyl ethylene carbonate (VEC), 1,3-propanesultone (PS),polydimethylsiloxane (PDMS), maleic anhydride (MA), and succinicanhydride (SA). 137-143. (canceled)